# Setting up Zoom Phone local survivability with Zoom Node Systems: Zoom Phone For Zoom Phone administrators with account owner or admin privilege who run a supported hypervisor at the sites they want to keep calling during a cloud outage. Canonical: https://warmtransfer.net/guides/zoom-phone-local-survivability-setup Last verified: 2026-10-01 Zoom Phone Local Survivability (ZPLS) is installed as a module on a Zoom Node server and acts as the third-priority registrar for supported devices, after the primary and secondary cloud SIP zones[^2][^52][^82]. When both the module and the devices cannot reach the site's SIP zones, users can dial internal extensions, hold, transfer, park, hold ad hoc 3-party conferences, and make PSTN calls where an SBC is integrated[^28][^29]. ## Before you start What survivability mode does and does not give users:[^29][^30] - During normal operation the ZPLS module handles no calls and only sends OPTIONS pings to the site's SIP zones[^82]. - Survivability mode engages only when both the ZPLS module and the client devices cannot reach the site-specific SIP zones[^28]. - Failover takes about three minutes, varying with the number of devices[^27]. - Active calls are not preserved at failover; users hear a fast busy tone and must re-establish the call[^1]. - Cloud service returns once the module has kept reliable SIP zone connectivity for about five minutes, and devices re-register with no admin or user action[^26]. - Voicemail, call pickup, auto receptionists, call queues, conferences of 4 or more parties, end-to-end encryption and call monitoring are unavailable in survivability mode[^30]. - Nomadic e911 calling is not available in survivability mode[^49]. - Site assignments are static, so users who roam to another location during an outage are not covered by that location's module[^75]. A multi-site design needs one module per survivability-enabled site, so take the following inventory for each protected site[^50]. - A hypervisor host running VMware ESXi 6.7 or higher, KVM Hypervisor, or Nutanix AHV[^43]. - A host CPU that is an Intel 3rd generation Xeon or newer (for example Silver 4316) with 8 or more cores, 16 GB or more RAM, and a 10 Gbps or faster NIC[^12]. - A static internal IPv4 address for each Zoom Node VM[^74]. - A count of the users and devices that will register at the site, which sets the module size[^71][^72]. - For PSTN in survivability mode, a customer-provided SBC connected to a legacy connection or to a SIP trunk over a cellular or alternate connection[^66]. - For PSTN in survivability mode, unassigned and assigned BYOC numbers at the site for the ELIN and for call forwarding targets[^19][^39]. See also [Setting up Zoom Phone BYOC with an SBC](https://warmtransfer.net/knowledge/zoom-phone-byoc-setup) and [Setting up Zoom Phone emergency calling](https://warmtransfer.net/knowledge/zoom-phone-emergency-calling-setup). ## What changes by situation - How will the site reach the PSTN during a cloud outage? No PSTN in survivability mode; internal calls only; Reuse the certified SBC already used for BYOC premises peering; Add a new certified SBC with a survivable trunk. - How many sites get survivability, and must they call each other during an outage? One site; Several sites, each surviving on its own; Several sites that reach each other through Call Bridge. - How many registrations does the largest protected site need? Up to 2,000 registrations (8 CPU / 16 GB); Up to 5,000 registrations (16 CPU / 16 GB); More than 5,000 at one site (node group). - Does each site need a standby module? One module per site; Add a redundant hot-standby module per site. - Which users register to the survivability module? Everyone at the site; Selected user groups; Individual users or common area devices. ## Step 1: Confirm account prerequisites and endpoints ### Do - Confirm the account is a Business, Education or Enterprise account with a Zoom Node subscription and a Zoom Phone subscription, and that you hold account owner or admin privilege[^55]. - Confirm the Zoom Phone Hybrid license for service instances, which the deployment article lists as a prerequisite for deploying the Local Survivability service[^54]. - Confirm Multiple Sites is enabled for Zoom Phone, because the Local Survivability service cannot be configured or enabled without it[^56]. - Confirm the endpoints: supported desk phones, the Zoom desktop app for Windows or macOS version 7.0.0 or higher, and the Zoom VDI client[^10]. ### Verify - Suggested check: confirm in the admin portal that every site you intend to protect is listed as its own site. - Suggested check: confirm that the desktop clients at each protected site report a version at or above the minimum. ## Step 2: Size the module for each protected site **Up to 2,000 registrations (8 CPU / 16 GB)** ### Do - Plan configuration option 1, 8 CPU and 16 GB RAM, which supports 2,000 total registrations, 240 concurrent calls, 2 calls per second and 60 registrations per second[^71]. - Plan one module per protected site, because each ZPLS module can be associated with only one site at a time[^50]. - When a site exceeds the module's endpoint capacity, the module accepts registrations first-come, first-served up to the maximum[^53]. ### Verify - Suggested check: count the users, common area devices and desk phones at the largest protected site and confirm the total is within this option's registration limit. **Up to 5,000 registrations (16 CPU / 16 GB)** ### Do - Plan configuration option 2, 16 CPU and 16 GB RAM, which supports 5,000 total registrations, 480 concurrent calls, 4 calls per second and 400 registrations per second[^72]. - Plan one module per protected site, because each ZPLS module can be associated with only one site at a time[^50]. - When a site exceeds the module's endpoint capacity, the module accepts registrations first-come, first-served up to the maximum[^53]. ### Verify - Suggested check: count the users, common area devices and desk phones at the largest protected site and confirm the total is within this option's registration limit. **More than 5,000 at one site (node group)** ### Do - Plan a node group of up to 20 nodes, which supports at most 100,000 registrations (5,000 per node) without redundancy, or 50,000 with redundancy enabled[^48]. - A node group is assigned to a site under the same path as a single module[^3]. - When a site exceeds the endpoint capacity, the ZPLS module accepts registrations first-come, first-served up to the maximum[^53]. ### Verify - Suggested check: confirm that the site's registration count stays under the node group ceiling that matches the redundancy choice made for this site. ## Step 3: Open the firewall paths **No PSTN in survivability mode; internal calls only** ### Do - Add the ZPLS rules on top of the standard Zoom Phone and Zoom Node firewall requirements[^31]. - Allow Zoom clients and desk phones to reach the ZPLS service on TCP 5091 for registration and UDP 20000-64000 for media, and allow the ZPLS service to send media back on UDP 20000-64000[^33]. - Allow the ZPLS service outbound on TCP 443 and 9669 to Zoom's IP ranges and on TCP 5091 to Zoom Phone's IP ranges[^35]. ### Verify - Once the node is deployed, run the Node console's network testing tool (option 2), whose Common Connectivity, Phone Connectivity and Diagnose Network tests check cloud reachability[^11]. ### Rollback - Suggested rollback: remove the rules added in this step and leave the standard rules in place. **Reuse the certified SBC already used for BYOC premises peering** ### Do - Add the ZPLS rules on top of the standard Zoom Phone and Zoom Node firewall requirements[^31]. - Allow Zoom clients and desk phones to reach the ZPLS service on TCP 5091 for registration and UDP 20000-64000 for media, and allow the ZPLS service to send media back on UDP 20000-64000[^33]. - Allow the ZPLS service outbound on TCP 443 and 9669 to Zoom's IP ranges and on TCP 5091 to Zoom Phone's IP ranges[^35]. - Allow SIP trunk signalling between the ZPLS service and the existing SBC on TCP 5061 in both directions, and SBC media to ZPLS on UDP 20000-64000[^34]. ### Verify - Once the node is deployed, run the Node console's network testing tool (option 2), whose Common Connectivity, Phone Connectivity and Diagnose Network tests check cloud reachability[^11]. ### Rollback - Suggested rollback: remove the rules added in this step and leave the standard rules in place. **Add a new certified SBC with a survivable trunk** ### Do - Add the ZPLS rules on top of the standard Zoom Phone and Zoom Node firewall requirements[^31]. - Allow Zoom clients and desk phones to reach the ZPLS service on TCP 5091 for registration and UDP 20000-64000 for media, and allow the ZPLS service to send media back on UDP 20000-64000[^33]. - Allow the ZPLS service outbound on TCP 443 and 9669 to Zoom's IP ranges and on TCP 5091 to Zoom Phone's IP ranges[^35]. - Allow SIP trunk signalling between the ZPLS service and the new SBC on TCP 5061 in both directions, and SBC media to ZPLS on UDP 20000-64000[^34]. ### Verify - Once the node is deployed, run the Node console's network testing tool (option 2), whose Common Connectivity, Phone Connectivity and Diagnose Network tests check cloud reachability[^11]. ### Rollback - Suggested rollback: remove the rules added in this step and leave the standard rules in place. ## Step 4: Deploy and register the Zoom Node VM **One module per site** ### Do - Download the Zoom Node OVA from Node Management > Modules with Zoom Node - Phone Local Survivability selected, under the Nodes tab via Add Nodes; it must be installed on the VM before the ZPLS module[^52]. - Deploy it on VMware ESXi 6.7 or higher, KVM Hypervisor, or Nutanix AHV[^43]. - From the virtual console, give the VM a static internal IPv4 address; direct access to the appliance is available only through the virtual console[^74]. - Generate a registration code in the Zoom web portal and enter it in the Node Agent interface on HTTPS port 8443[^58]. - Deploy one such VM per protected site, since a multi-site design needs one module per survivability-enabled site[^50]. ### Verify - After registration, the Monitor Agent and Node Agent must show as running[^58]. ### Rollback - Suggested rollback: power off and delete the virtual machine, then remove the node from the admin portal. **Add a redundant hot-standby module per site** ### Do - Download the Zoom Node OVA from Node Management > Modules with Zoom Node - Phone Local Survivability selected, under the Nodes tab via Add Nodes; it must be installed on the VM before the ZPLS module[^52]. - Deploy it on VMware ESXi 6.7 or higher, KVM Hypervisor, or Nutanix AHV[^43]. - From the virtual console, give the VM a static internal IPv4 address; direct access to the appliance is available only through the virtual console[^74]. - Generate a registration code in the Zoom web portal and enter it in the Node Agent interface on HTTPS port 8443[^58]. - Deploy an additional VM per site for the redundant module, which adds no registration capacity, stays on hot standby and engages only if a primary module fails[^57]. ### Verify - On every VM, primary and standby, the Monitor Agent and Node Agent must show as running[^58]. ### Rollback - Suggested rollback: power off and delete the standby virtual machine, then remove its node from the admin portal. ## Step 5: Add the Local Survivability service on the node ### Do - Go to Node Management > Modules > Phone Local Survivability > Services > Add Services > Local Survivability, and choose the Node server, an internal IP address and an optional internal domain prefix[^2]. ### Verify - After installation the ZPLS module shows Stopped, and it must not be started until it has been assigned to a site[^15]. ### Rollback - Suggested rollback: remove the service from the node's services list while it is still stopped. ## Step 6: Assign the module to its site and start it ### Do - Go to Phone System Management > Company Info > Account Settings > Zoom Node > Local Survivability > Manage > Assign to, and choose the site for the module or node group[^3]. - Select the assigned module on the Zoom Node Services tab and click Start, then allow at least 3 minutes for the status to change from Stopped to Running[^73]. ### Verify - Under the site's Settings tab > Zoom Node > Local Survivability > Manage, an operational module shows as Running with its current version and IP address[^84]. ### Rollback - Suggested rollback: stop the module, then remove its site assignment. ## Step 7: Extend survivability across sites **One site** ### Do - Each ZPLS module can be associated with only one site at a time, so a single protected site needs only the module already deployed and assigned[^50]. ### Verify - Suggested check: confirm that exactly one site shows a running survivability module. **Several sites, each surviving on its own** ### Do - Repeat the sizing, deployment, service and site-assignment steps for each additional site, since a multi-site design needs one module per survivability-enabled site[^50]. - A campus network outage breaks cross-site calling between ZPLS sites unless each site has an SBC with PSTN connectivity and call forwarding enabled; include that in user communications[^8]. ### Verify - Each site shows its own module as Running, with its version and IP address, under the site's Settings tab > Zoom Node > Local Survivability > Manage[^84]. ### Rollback - Suggested rollback: for any site you no longer want protected, stop its module and remove its site assignment. **Several sites that reach each other through Call Bridge** ### Do - Repeat the sizing, deployment, service and site-assignment steps for each additional site, since a multi-site design needs one module per survivability-enabled site[^50]. - Deploy the Call Bridge, which routes calls between ZPLS modules or node groups during an outage, on a standalone Node server reachable by all ZPLS modules[^7]. - Add it from Node Management > Modules > Phone Local Survivability > Services > Add Services > Call Bridge, then assign it under Account Settings > Local Survivability > Shared database nodes > Edit[^5]. - Allow traffic on TCP 9443 from the ZPLS service toward other ZPLS nodes and the Call Bridge, which carries signalling, media and data synchronisation between nodes and node groups[^32]. - Call Bridge supports node-to-node, node-to-node-group and node-group-to-node-group calling, and calls between nodes inside one node group do not need it[^4]. ### Verify - If the originating ZPLS node loses its connection to the Call Bridge, it cannot locate the destination node, and calls to users on other nodes or node groups fail[^6]. - Suggested check: during the failover test, place a call between users at two different protected sites and confirm it connects. ### Rollback - Suggested rollback: remove the bridge from the shared database assignment, then delete the bridge service. ## Step 8: Integrate the SBC for PSTN breakout **No PSTN in survivability mode; internal calls only** ### Do - PSTN calling during survivability requires a customer-provided SBC connected to a legacy connection or to a SIP trunk over a cellular or alternate connection, so a site without one has no PSTN breakout in survivability mode[^66]. ### Verify - Suggested check: confirm that no survivability route group is assigned to this site's module. **Reuse the certified SBC already used for BYOC premises peering** ### Do - Zoom states that any SBC certified for Zoom Phone can be used with the ZPLS module, so customers already on a Zoom Phone BYOC plan need no separate SBC for survivability[^63]. - Install Zoom's DigiCert root and intermediate certificates on the SBC for TLS connectivity with the ZPLS module[^65]. - Make sure the SBC's entry under the site's Settings > Routing > Session Border Controllers carries its public IP and port, a Survivability public or private address and port, and has In Service and Send OPTIONS ping turned on[^62]. - Create a route group under Routing > Route Groups > Manage > Add with Type set to Survivability and the SBC selected, then assign it to the ZPLS server under Account Settings > Zoom Node > Local Survivability > Manage > Edit[^60]. - Adding an SBC in the portal does not create the SIP trunk to ZPLS; the SBC must belong to a Survivability route group associated with the site or account[^76]. - Keep the SBC routing inbound PSTN calls to the primary and secondary Zoom SIP zones before trying the ZPLS module[^64]. - Optionally preserve site-level routing rules during survivability by turning on Enable Routing Rules in the site's Zoom Node section[^61]. ### Verify - Once the route group is assigned, the ZPLS module tries to establish a TLS connection with the SBC, and OPTIONS pings, if enabled, verify ongoing connectivity[^83]. ### Rollback - Suggested rollback: unassign the survivability route group from the module and delete it, then clear the survivability address from the trunk device's entry. **Add a new certified SBC with a survivable trunk** ### Do - Deploy an SBC that supports TLS 1.2, SRTP, mutual TLS, SIP, RFC 2833 DTMF, RFC 5853 topology hiding, mandatory SIP Early Offer, and the Opus, G.711 mu-law, G.711 A-law and G.729 codecs[^67]. - Connect it to a legacy connection or to a SIP trunk over a cellular or alternate connection[^66]. - Add it under the site's Settings > Routing > Session Border Controllers > Manage > Add, with its public IP and port, a Survivability public or private address and port, and In Service and Send OPTIONS ping turned on[^62]. - Install Zoom's DigiCert root and intermediate certificates on the SBC for TLS connectivity with the ZPLS module[^65]. - Create a route group under Routing > Route Groups > Manage > Add with Type set to Survivability and the SBC selected, then assign it to the ZPLS server under Account Settings > Zoom Node > Local Survivability > Manage > Edit[^60]. - Adding an SBC in the portal does not create the SIP trunk to ZPLS; the SBC must belong to a Survivability route group associated with the site or account[^76]. - Configure the SBC to route inbound PSTN calls to the primary and secondary Zoom SIP zones before trying the ZPLS module[^64]. ### Verify - Once the route group is assigned, the ZPLS module tries to establish a TLS connection with the SBC, and OPTIONS pings, if enabled, verify ongoing connectivity[^83]. ### Rollback - Suggested rollback: unassign and delete the survivability route group, then delete the new trunk device's entry. ## Step 9: Configure emergency calling (ELIN) **No PSTN in survivability mode; internal calls only** ### Do - Do not configure an ELIN for this site, because the ELIN must be a BYOC number terminated on a PSTN trunk at the site's failover SBC and no other type of number can be used[^17]. - In the US, 47 CFR 9.16 requires an MLTS to let a user dial 911 directly from any station without an additional digit, code, prefix or post-fix, and to notify a central location at the facility[^45]. - In the US, 47 CFR 9.16 also requires an MLTS to be able to send the caller's dispatchable location to the PSAP with 911 calls[^46]. ### Verify - Suggested check: have the person responsible for emergency-calling compliance review and sign off on the absence of a local emergency calling path at this site during an outage. **Reuse the certified SBC already used for BYOC premises peering** ### Do - Under the site's Settings > Zoom Node > Emergency Location Identification Number (ELIN) > Add Number, add one unassigned BYOC number and keep it unassigned to any user; each site supports one ELIN[^19]. - Use a number terminated on a PSTN trunk at the site's failover SBC, since no other type of number can be used[^17]. - Maintain and update the physical address associated with the ELIN yourself, as customers are responsible for it[^16]. - In the US, 47 CFR 9.16 requires direct 911 dialing with notification to a central location, and the ability to send the caller's dispatchable location to the PSAP[^45][^46]. ### Verify - For up to 2 hours, the ZPLS module routes emergency-provider callbacks to the ELIN back to the extension that originally dialled[^18]. - Suggested check: coordinate with the carrier and the local emergency answering point before placing any test emergency call during the failover test. ### Rollback - Suggested rollback: remove the number from the site's ELIN setting. **Add a new certified SBC with a survivable trunk** ### Do - Under the site's Settings > Zoom Node > Emergency Location Identification Number (ELIN) > Add Number, add one unassigned BYOC number and keep it unassigned to any user; each site supports one ELIN[^19]. - Use a number terminated on a PSTN trunk at the new failover SBC, since no other type of number can be used[^17]. - Maintain and update the physical address associated with the ELIN yourself, as customers are responsible for it[^16]. - In the US, 47 CFR 9.16 requires direct 911 dialing with notification to a central location, and the ability to send the caller's dispatchable location to the PSAP[^45][^46]. ### Verify - For up to 2 hours, the ZPLS module routes emergency-provider callbacks to the ELIN back to the extension that originally dialled[^18]. - Suggested check: coordinate with the carrier and the local emergency answering point before placing any test emergency call during the failover test. ### Rollback - Suggested rollback: remove the number from the site's ELIN setting. ## Step 10: Prepare inbound call handling for an outage **No PSTN in survivability mode; internal calls only** ### Do - During a survivability event, Zoom-provided phone numbers are not reachable from outside unless they are re-routed through call forwarding[^47]. - Call Forwarding Local Survivability forwards those calls across the PSTN to BYOC-P numbers at the ZPLS site, which this site does not have[^42]. - A Survivable Distribution Group that routes by phone number requires a configured BYOC PSTN integration[^69]. - Auto receptionists and call queues are unavailable in survivability mode[^30]. ### Verify - Suggested check: confirm that the site's outage communication tells users that inbound external calls will not arrive during an outage. **Reuse the certified SBC already used for BYOC premises peering** ### Do - Under the site's Settings > Zoom Node > Call Forwarding Local Survivability > Manage > Add, pair each source number with a BYOC number enabled for Local Survivability and assigned to a user in the site[^39]. - Leave out the main company number, which cannot be configured for Call Forwarding Local Survivability[^38]. - Keep forwarding disabled during normal operation[^36]. - Optionally create a Survivable Distribution Group under the site's Settings > Zoom Node > Survivable Distribution Group > Manage > Add, configured much like a call queue via Edit[^68]. - Calls to an auto receptionist, call queue or shared line group can be forwarded to that group in survivability mode[^70]. ### Verify - Each source number's forwarding status is disabled by default, and an admin enables it with Enable Forwarding only during an outage[^36]. ### Rollback - Suggested rollback: delete the forwarding mappings and any distribution group created in this step. **Add a new certified SBC with a survivable trunk** ### Do - Under the site's Settings > Zoom Node > Call Forwarding Local Survivability > Manage > Add, pair each source number with a BYOC number on the new trunk that is enabled for Local Survivability and assigned to a user in the site[^39]. - Leave out the main company number, which cannot be configured for Call Forwarding Local Survivability[^38]. - Keep forwarding disabled during normal operation[^36]. - Optionally create a Survivable Distribution Group under the site's Settings > Zoom Node > Survivable Distribution Group > Manage > Add, configured much like a call queue via Edit[^68]. - Calls to an auto receptionist, call queue or shared line group can be forwarded to that group in survivability mode[^70]. ### Verify - Each source number's forwarding status is disabled by default, and an admin enables it with Enable Forwarding only during an outage[^36]. ### Rollback - Suggested rollback: delete the forwarding mappings and any distribution group created in this step. ## Step 11: Turn on Local Survivability at account level ### Do - Once the service status is Running, enable Local Survivability under Phone System Management > Company Info > Account Settings > Zoom Node[^21]. - The field guide gives the account-wide registration toggle as the Local Survivability Mode setting under Account Management > Account Settings > Zoom Phone tab, so check that setting too[^22]. ### Verify - Suggested check: confirm that both account-level settings show as enabled. ### Rollback - Suggested rollback: turn both account-level settings off. ## Step 12: Enable users for survivability **Everyone at the site** ### Do - Enable Local Survivability Mode on the site's Policy tab, which makes all users in that site automatically attempt to connect to the site's ZPLS module[^24]. - Site changes, including added or modified users and devices, are synchronised to the ZPLS module once every 10 hours[^77]. ### Verify - Group policies override site policies, so check that no group setting for these users disables Local Survivability Mode[^23]. - A per-user or per-device setting overrides all others unless they are locked[^25]. ### Rollback - Suggested rollback: turn the site policy setting off. **Selected user groups** ### Do - Set Local Survivability Mode for each chosen group under User Management > Groups > Zoom Phone tab, optionally locked[^23]. - Site changes, including added or modified users and devices, are synchronised to the ZPLS module once every 10 hours[^77]. ### Verify - Group policies override site policies[^23]. - A per-user or per-device setting overrides the group setting unless it is locked[^25]. - Suggested check: open a sample of group members and confirm the setting shows as enabled on each. ### Rollback - Suggested rollback: turn the group setting off. **Individual users or common area devices** ### Do - Set Local Survivability Mode per user under Users & Rooms > user > Policy tab, or per common area device under Common Areas > device > Policy tab[^25]. - Site changes, including added or modified users and devices, are synchronised to the ZPLS module once every 10 hours[^77]. ### Verify - The per-user or per-device setting overrides all others unless they are locked[^25]. - Suggested check: confirm that no locked site or group setting blocks the per-user setting. ### Rollback - Suggested rollback: turn the per-user or per-device setting off. ## Step 13: Test failover ### Do - For a desktop-client check without a real outage, use Testing Mode: after a module restart, the module accepts new registrations from desktop clients whose users sign out and back in, while IP phones and existing registrations are unaffected[^79]. - For a full test, block all connections to the Zoom Phone network[^78]. - Block both device-to-cloud and module-to-cloud traffic, because the module accepts no SIP registrations unless its OPTIONS keepalive to the cloud has failed[^51]. - Allow about three minutes for failover, varying with the number of devices[^27]. ### Verify - On the client, Settings > Statistics > Phone tab shows a Register Server IP and port that match the ZPLS module[^78]. - Internal extension dialling, consult and blind transfers, call park and, where an SBC is integrated, PSTN calls should work[^29]. - After connectivity returns, devices re-register to the cloud once the module has kept reliable SIP zone connectivity for about five minutes[^26]. - After exiting survivability mode, the module uploads call detail records for the calls made during the event, marked as survivability-mode calls[^9]. ### Rollback - Restore connectivity to the Zoom Phone network after the full test[^78]. - Suggested rollback: switch testing mode off once the desktop-client check is complete. ## Step 14: Write the outage runbook **No PSTN in survivability mode; internal calls only** ### Do - Tell users that active calls drop at failover with a fast busy tone and must be re-established[^1]. - List the features that stop working: voicemail, call pickup, auto receptionists, call queues, conferences of 4 or more parties, end-to-end encryption and call monitoring[^30]. - Note that without an SBC there is no PSTN calling in survivability mode[^66]. - Note that users who roam to another location during an outage are not covered by that location's module[^75]. - Note that devices re-register to the cloud with no admin or user action once connectivity has been stable for about five minutes[^26]. ### Verify - Suggested check: walk through the runbook with site staff during the next scheduled failover test. **Reuse the certified SBC already used for BYOC premises peering** ### Do - Add a step for an admin to select Enable Forwarding at the start of an outage, since forwarding stays disabled during normal operation[^36]. - Plan how that admin reaches the Zoom web portal, because enabling call forwarding during a survivability event requires a working internet connection[^40]. - Add a step to select Disable Forwarding and confirm once service returns[^37]. - Keep the PSTN and local internet paths independent, since call forwarding in survivability relies on paths that do not fail together[^41]. - Tell users that active calls drop at failover and that voicemail, call pickup, auto receptionists and call queues are unavailable[^1][^30]. ### Verify - Call Forwarding Local Survivability forwards calls to Zoom-provided numbers across the PSTN to BYOC-P numbers at the ZPLS site in survivability mode[^42]. - Suggested check: during the next failover test, call a mapped number from an outside line and confirm it rings at its mapped destination. ### Rollback - Turn forwarding off by selecting Disable Forwarding and confirming[^37]. **Add a new certified SBC with a survivable trunk** ### Do - Add a step for an admin to select Enable Forwarding at the start of an outage, since forwarding stays disabled during normal operation[^36]. - Plan how that admin reaches the Zoom web portal, because enabling call forwarding during a survivability event requires a working internet connection[^40]. - Add a step to select Disable Forwarding and confirm once service returns[^37]. - Keep the new trunk's PSTN path independent of the site's internet path, since call forwarding in survivability relies on paths that do not fail together[^41]. - Tell users that active calls drop at failover and that voicemail, call pickup, auto receptionists and call queues are unavailable[^1][^30]. ### Verify - Call Forwarding Local Survivability forwards calls to Zoom-provided numbers across the PSTN to BYOC-P numbers at the ZPLS site in survivability mode[^42]. - Suggested check: during the next failover test, call a mapped number from an outside line and confirm it rings at its mapped destination. ### Rollback - Turn forwarding off by selecting Disable Forwarding and confirming[^37]. ## Applicability Applies to: Zoom Phone Local Survivability and Zoom Node. Deployments: hybrid and any. Sources checked 2026-10-02. The latest ZPLS release, dated 2026-09-21, is ZPLS service 5.9.0.20260914.275 with Call Bridge 1.9.0.20260914.64, and contains minor Node platform bug fixes[^59]. The release of 2026-06-22 (5.6.0.20260618.253) lets account owners and admins manually enable ZPLS so that Zoom apps and desk phones keep working during an outage[^44]. The 47 CFR 9.16 emergency-calling requirements cited in the ELIN step are US rules[^45][^46]. ## What remains uncertain - The disk size and disk provisioning type for the Zoom Node VM are not covered by the sources below. - The procedure for using the manual enable option is not covered by the sources below. - Where Testing Mode is switched on and off in the portal is not covered by the sources below. - Whether the two account-level toggles are the same setting reached by different paths is not covered by the sources below. - How the Local Survivability service is added and assigned on a hot-standby module is not covered by the sources below. - Vendor-specific SBC configuration for survivability trunks is not covered by the sources below. - The specific desk phone models and firmware supported in survivability mode are not covered by the sources below. - Whether a single site-level ELIN satisfies dispatchable-location obligations for a large or multi-floor site is not covered by the sources below. - Survivability designs that do not use Zoom Node are not covered by the sources below. ## Sources [^1]: Active calls are not preserved when survivability mode engages; users hear a fast busy tone and must re-establish the call. Source: [Zoom Phone Local Survivability | Zoom Technical Library](https://library.zoom.com/advanced-enterprise-services/zoom-node/zoom-node-explainer/zoom-phone-local-survivability), Failover - call impact. Checked 2026-10-01. [^2]: The ZPLS module is installed from Node Management > Modules > Phone Local Survivability > Services > Add Services > Local Survivability by choosing the Node server, an internal IP address and an optional internal domain prefix. Source: [Deploying the Zoom Phone Local Survivability service](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0061895), How to deploy the service. Checked 2026-10-01. [^3]: A ZPLS module (or a node group) is assigned to a site under Phone System Management > Company Info > Account Settings > Zoom Node > Local Survivability > Manage > Assign to. Source: [Configuring the Zoom Phone Local Survivability service](https://support.zoom.us/hc/en-us/articles/8427674303373-Configuring-Zoom-Phone-Local-Survivability-service-module), Assigning the module to a site. Checked 2026-10-01. [^4]: Call Bridge supports node-to-node, node-to-node-group and node-group-to-node-group calling; calls between nodes inside one node group do not need it. Source: [Deploying the Call Bridge service for Zoom Phone Local Survivability](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0085763), Supported cases. Checked 2026-10-01. [^5]: Call Bridge is deployed from Node Management > Modules > Phone Local Survivability > Services > Add Services > Call Bridge, then assigned under Account Settings > Local Survivability > Shared database nodes > Edit. Source: [Deploying the Call Bridge service for Zoom Phone Local Survivability](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0085763), How to deploy and assign the Call Bridge. Checked 2026-10-01. [^6]: If the originating ZPLS node loses its connection to the Call Bridge, it cannot locate the destination node, and calls to users on other nodes or node groups fail. Source: [Deploying the Call Bridge service for Zoom Phone Local Survivability](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0085763), Network resiliency considerations. Checked 2026-10-01. [^7]: The Call Bridge (shared database nodes), which routes calls between ZPLS modules or node groups during an outage, must run on a standalone Node server reachable by all ZPLS modules. Source: [Deploying the Call Bridge service for Zoom Phone Local Survivability](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0085763), Overview and deployment requirements. Checked 2026-10-01. [^8]: A campus network outage breaks cross-site calling between ZPLS sites unless each site has an SBC with PSTN connectivity and call forwarding enabled. Source: [ZPLS Field Guide - Hardware Deployment Considerations](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/before-you-begin/hardware-deployment-considerations), Network failure scenarios. Checked 2026-10-01. [^9]: After exiting survivability mode, the ZPLS module uploads call detail records for the calls made during the event, marked as survivability-mode calls. Source: [Zoom Phone Local Survivability | Zoom Technical Library](https://library.zoom.com/advanced-enterprise-services/zoom-node/zoom-node-explainer/zoom-phone-local-survivability), Call records. Checked 2026-10-01. [^10]: Supported endpoints for survivability are supported desk phones, the Zoom desktop app for Windows or macOS version 7.0.0 or higher, and the Zoom VDI client. Source: [Getting started with Zoom Phone Local Survivability service](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0058798), Supported devices. Checked 2026-10-01. [^11]: The Node console has a network testing tool (option 2) with Common Connectivity, Phone Connectivity and Diagnose Network tests to check cloud reachability. Source: [ZPLS Field Guide - Troubleshooting](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/troubleshooting), Verify cloud connectivity. Checked 2026-10-01. [^12]: Each ZPLS VM host needs an Intel 3rd generation Xeon or newer CPU (for example Silver 4316) with 8 or more cores, 16 GB or more RAM, and a 10 Gbps or faster NIC. Source: [System requirements for the Zoom Phone Local Survivability service](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0060830), CPU, RAM and Network requirements. Checked 2026-10-01. [^13]: The ZPLS system requirements article requires 200 GB or more of storage per VM host (disputed). Source: [System requirements for the Zoom Phone Local Survivability service](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0060830), Disk / storage requirement. Checked 2026-10-01. [^14]: The ZPLS field guide sizes both configuration options with an 80 GB HDD (disputed). Source: [ZPLS Field Guide - Hardware Deployment Considerations](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/before-you-begin/hardware-deployment-considerations), Hardware Deployment Considerations - configuration options 1 and 2. Checked 2026-10-01. [^15]: After installation the ZPLS module shows Stopped, and it must not be started until it has been assigned to a site. Source: [Deploying the Zoom Phone Local Survivability service](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0061895), How to deploy the service - final note. Checked 2026-10-01. [^16]: Customers are responsible for maintaining and updating the physical address associated with each site's ELIN. Source: [PSTN Integration Considerations | Zoom Technical Library](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/before-you-begin/pstn-integration-considerations), Emergency Location Identification Number. Checked 2026-10-01. [^17]: The ELIN must be a BYOC number terminated on a PSTN trunk at the site's failover SBC; no other type of number can be used. Source: [PSTN Integration Considerations | Zoom Technical Library](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/before-you-begin/pstn-integration-considerations), Emergency Location Identification Number. Checked 2026-10-01. [^18]: For up to 2 hours, the ZPLS module routes emergency-provider callbacks to the ELIN back to the extension that originally dialled. Source: [PSTN Integration Considerations | Zoom Technical Library](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/before-you-begin/pstn-integration-considerations), Emergency Location Identification Number. Checked 2026-10-01. [^19]: Each site supports one ELIN, set under the site's Settings > Zoom Node > Emergency Location Identification Number (ELIN) > Add Number with an unassigned BYOC number that must stay unassigned to any user. Source: [Configuring the Zoom Phone Local Survivability service](https://support.zoom.us/hc/en-us/articles/8427674303373-Configuring-Zoom-Phone-Local-Survivability-service-module), Configuring the ELIN. Checked 2026-10-01. [^20]: Because a site has a single ELIN, every survivability-mode 911 call from that site gives the PSAP the same site-level location, which may not meet dispatchable-location expectations for a multi-floor or multi-building site (inferred). Source: [Configuring the Zoom Phone Local Survivability service](https://support.zoom.us/hc/en-us/articles/8427674303373-Configuring-Zoom-Phone-Local-Survivability-service-module), Configuring the ELIN (one ELIN per site), read with 47 CFR 9.16. Checked 2026-10-01. [^21]: At account level, once the service status is Running, Local Survivability is enabled under Phone System Management > Company Info > Account Settings > Zoom Node. Source: [Enabling the Zoom Phone Local Survivability service](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0062795), Account level. Checked 2026-10-01. [^22]: The field guide gives the account-wide registration toggle as the Local Survivability Mode setting under Account Management > Account Settings > Zoom Phone tab. Source: [ZPLS Field Guide - Enable Users for ZPLS](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/enable-users-for-zpls), Account-wide registration. Checked 2026-10-01. [^23]: Local Survivability Mode can be set per group under User Management > Groups > Zoom Phone tab, optionally locked, and group policies override site policies. Source: [ZPLS Field Guide - Enable Users for ZPLS](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/enable-users-for-zpls), Group-wide registration. Checked 2026-10-01. [^24]: Enabling Local Survivability Mode on a site's Policy tab makes all users in that site automatically attempt to connect to the site's ZPLS module. Source: [ZPLS Field Guide - Enable Users for ZPLS](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/enable-users-for-zpls), Site-wide registration. Checked 2026-10-01. [^25]: Local Survivability Mode can be set per user (Users & Rooms > user > Policy tab) or per common area device (Common Areas > device > Policy tab), and that setting overrides all others unless they are locked. Source: [ZPLS Field Guide - Enable Users for ZPLS](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/enable-users-for-zpls), Per-user and per-device registration. Checked 2026-10-01. [^26]: Cloud service and routing are restored once the ZPLS module has kept reliable SIP zone connectivity for about five minutes, and devices re-register with no admin or user action. Source: [Zoom Phone Local Survivability | Zoom Technical Library](https://library.zoom.com/advanced-enterprise-services/zoom-node/zoom-node-explainer/zoom-phone-local-survivability), Failback. Checked 2026-10-01. [^27]: Failover into survivability mode takes about three minutes, varying with the number of devices. Source: [Zoom Phone Local Survivability | Zoom Technical Library](https://library.zoom.com/advanced-enterprise-services/zoom-node/zoom-node-explainer/zoom-phone-local-survivability), Failover. Checked 2026-10-01. [^28]: Survivability mode engages only when both the ZPLS module and the client devices cannot reach the site-specific SIP zones. Source: [Zoom Phone Local Survivability | Zoom Technical Library](https://library.zoom.com/advanced-enterprise-services/zoom-node/zoom-node-explainer/zoom-phone-local-survivability), Failover. Checked 2026-10-01. [^29]: In survivability mode, users can dial internal extensions, dial from contacts and call history, hold and resume, mute, send RFC 2833 DTMF, make consult and blind transfers, park calls (ringback to the parker only), hold ad hoc 3-party conferences, and make PSTN calls when an SBC is integrated. Source: [Getting started with Zoom Phone Local Survivability service](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0058798), Supported features during survivability. Checked 2026-10-01. [^30]: Voicemail, call pickup, auto receptionists, call queues, conferences of 4 or more parties, end-to-end encryption and call monitoring are unavailable in survivability mode. Source: [Zoom Phone Local Survivability | Zoom Technical Library](https://library.zoom.com/advanced-enterprise-services/zoom-node/zoom-node-explainer/zoom-phone-local-survivability), Features not available in survivability mode. Checked 2026-10-01. [^31]: The ZPLS firewall rules apply in addition to the standard Zoom Phone and Zoom Node firewall requirements. Source: [Firewall requirements for Zoom Phone Local Survivability](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0058005), Notes below the rules table. Checked 2026-10-01. [^32]: The ZPLS service uses TCP 9443 toward other ZPLS nodes and the Call Bridge for signalling, media and data synchronisation between nodes and node groups. Source: [Firewall requirements for Zoom Phone Local Survivability](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0058005), Firewall rules table - TCP 9443 row and asterisk note. Checked 2026-10-01. [^33]: Zoom clients and desk phones must reach the ZPLS service on TCP 5091 for registration and UDP 20000-64000 for media, and the ZPLS service sends media back on UDP 20000-64000. Source: [Firewall requirements for Zoom Phone Local Survivability](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0058005), Firewall rules table - client/deskphone rows. Checked 2026-10-01. [^34]: The ZPLS service and the customer SBC exchange SIP trunk signalling on TCP 5061 in both directions, and SBC media to ZPLS uses UDP 20000-64000. Source: [Firewall requirements for Zoom Phone Local Survivability](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0058005), Firewall rules table - SBC rows. Checked 2026-10-01. [^35]: The ZPLS service needs outbound TCP 443 and 9669 to Zoom's IP ranges and TCP 5091 to Zoom Phone's IP ranges. Source: [Firewall requirements for Zoom Phone Local Survivability](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0058005), Firewall rules table - ZPLS to Zoom rows. Checked 2026-10-01. [^36]: Each source number's forwarding status is disabled by default; an admin enables it with Enable Forwarding only during an outage and keeps it disabled during normal operation. Source: [Configuring call forwarding for Zoom Phone Local Survivability](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0085766), Enabling call forwarding during an outage. Checked 2026-10-01. [^37]: Forwarding is turned off by the same path, selecting Disable Forwarding and confirming. Source: [ZPLS Field Guide - (Optional) Enabling Call Forwarding During a Survivability Event](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/optional-tasks/optional-enabling-call-forwarding-during-a-survivability-event), Disabling call forwarding. Checked 2026-10-01. [^38]: The main company number cannot be configured for Call Forwarding Local Survivability. Source: [Configuring call forwarding for Zoom Phone Local Survivability](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0085766), Notes / limitations. Checked 2026-10-01. [^39]: Forwarding is mapped under the site's Settings > Zoom Node > Call Forwarding Local Survivability > Manage > Add, pairing source numbers with BYOC numbers enabled for Local Survivability and assigned to users in the site. Source: [Configuring call forwarding for Zoom Phone Local Survivability](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0085766), How to configure call forwarding. Checked 2026-10-01. [^40]: Enabling call forwarding during a survivability event requires an admin to reach the Zoom web portal over a working internet connection. Source: [ZPLS Field Guide - (Optional) Enabling Call Forwarding During a Survivability Event](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/optional-tasks/optional-enabling-call-forwarding-during-a-survivability-event), Requirements. Checked 2026-10-01. [^41]: Call forwarding in survivability relies on PSTN and local internet paths that do not fail together. Source: [Configuring call forwarding for Zoom Phone Local Survivability](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0085766), Notes / limitations. Checked 2026-10-01. [^42]: Call Forwarding Local Survivability forwards calls to Zoom-provided numbers across the PSTN to BYOC-P numbers at the ZPLS site when the system is in survivability mode. Source: [Configuring call forwarding for Zoom Phone Local Survivability](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0085766), Overview. Checked 2026-10-01. [^43]: The ZPLS service supports VMware ESXi 6.7 or higher, KVM Hypervisor, or Nutanix AHV as the hypervisor. Source: [System requirements for the Zoom Phone Local Survivability service](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0060830), Hypervisor requirement. Checked 2026-10-01. [^44]: The ZPLS release of 2026-06-22 (5.6.0.20260618.253) lets account owners and admins manually enable ZPLS so that Zoom apps and desk phones keep working during an outage. Source: [Release notes for Zoom Phone Local Survivability module](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0069671), June 22, 2026 entry. Checked 2026-10-01. [^45]: Under 47 CFR 9.16, an MLTS must let a user dial 911 directly from any station without an additional digit, code, prefix or post-fix, and must notify a central location at the facility. Source: [47 CFR part 9 — 911 Requirements](https://www.ecfr.gov/current/title-47/chapter-I/subchapter-A/part-9), 47 CFR 9.16(a)(1), (b)(1), (b)(2). Checked 2026-10-01. [^46]: Under 47 CFR 9.16, an MLTS must be able to send the caller's dispatchable location to the PSAP with 911 calls; fixed devices had to comply from January 6, 2021 and non-fixed devices from January 6, 2022. Source: [47 CFR part 9 — 911 Requirements](https://www.ecfr.gov/current/title-47/chapter-I/subchapter-A/part-9), 47 CFR 9.16(a)(2), (b)(3). Checked 2026-10-01. [^47]: During a survivability event, Zoom-provided phone numbers are not reachable from outside unless they are re-routed through call forwarding. Source: [PSTN Integration Considerations | Zoom Technical Library](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/before-you-begin/pstn-integration-considerations), Zoom Phone native numbers. Checked 2026-10-01. [^48]: A ZPLS node group of up to 20 nodes supports at most 100,000 registrations (5,000 per node) without redundancy, or 50,000 with redundancy enabled. Source: [System requirements for the Zoom Phone Local Survivability service](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0060830), Registrations - Node group. Checked 2026-10-01. [^49]: Nomadic e911 calling is not available in survivability mode. Source: [Zoom Phone Local Survivability | Zoom Technical Library](https://library.zoom.com/advanced-enterprise-services/zoom-node/zoom-node-explainer/zoom-phone-local-survivability), Features not available in survivability mode. Checked 2026-10-01. [^50]: Each ZPLS module can be associated with only one site at a time, and a multi-site design needs one module per survivability-enabled site. Source: [ZPLS Field Guide - Hardware Deployment Considerations](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/before-you-begin/hardware-deployment-considerations), Site design considerations. Checked 2026-10-01. [^51]: The ZPLS module accepts no SIP registrations unless its OPTIONS keepalive to the cloud has failed, so a failover test must block both device-to-cloud and module-to-cloud traffic. Source: [ZPLS Field Guide - Troubleshooting](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/troubleshooting), Simulating a failover. Checked 2026-10-01. [^52]: The Zoom Node OVA is downloaded from Node Management > Modules with Zoom Node - Phone Local Survivability selected, under the Nodes tab via Add Nodes, and must be installed on the VM before the ZPLS module. Source: [ZPLS Field Guide - Deploy the ZPLS Module](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/deploy-the-zpls-module), Deploy the ZPLS Module - OVA download. Checked 2026-10-01. [^53]: When a survivability-enabled site exceeds the module's endpoint capacity, the ZPLS module accepts registrations first-come, first-served up to the maximum. Source: [System requirements for the Zoom Phone Local Survivability service](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0060830), Registrations note. Checked 2026-10-01. [^54]: The deployment article lists a Zoom Phone Hybrid license for service instances as a prerequisite for deploying the Local Survivability service. Source: [Deploying the Zoom Phone Local Survivability service](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0061895), Prerequisites. Checked 2026-10-01. [^55]: Configuring Zoom Phone Local Survivability requires a Business, Education or Enterprise account, a Zoom Node subscription, a Zoom Phone subscription, and account owner or admin privilege. Source: [Configuring the Zoom Phone Local Survivability service](https://support.zoom.us/hc/en-us/articles/8427674303373-Configuring-Zoom-Phone-Local-Survivability-service-module), Prerequisites. Checked 2026-10-01. [^56]: Multiple Sites must be enabled for Zoom Phone before the Local Survivability service can be configured or enabled. Source: [Configuring the Zoom Phone Local Survivability service](https://support.zoom.us/hc/en-us/articles/8427674303373-Configuring-Zoom-Phone-Local-Survivability-service-module), Prerequisites. Checked 2026-10-01. [^57]: Redundant ZPLS modules add no registration capacity; they stay on hot standby and engage only if a primary module fails. Source: [ZPLS Field Guide - Hardware Deployment Considerations](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/before-you-begin/hardware-deployment-considerations), Scaling and redundancy. Checked 2026-10-01. [^58]: The Node is registered by generating a registration code in the Zoom web portal and entering it in the Node Agent interface (HTTPS port 8443), after which the Monitor Agent and Node Agent must show as running. Source: [ZPLS Field Guide - Deploy the ZPLS Module](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/deploy-the-zpls-module), Deploy the ZPLS Module - register node and confirm agents. Checked 2026-10-01. [^59]: The latest ZPLS release, dated 2026-09-21, is ZPLS service 5.9.0.20260914.275 with Call Bridge 1.9.0.20260914.64, and contains minor Node platform bug fixes. Source: [Release notes for Zoom Phone Local Survivability module](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0069671), September 21, 2026 entry. Checked 2026-10-01. [^60]: The survivability route group is created under Routing > Route Groups > Manage > Add with Type set to Survivability and the SBC selected, then assigned to the ZPLS server under Account Settings > Zoom Node > Local Survivability > Manage > Edit. Source: [ZPLS Field Guide - (Optional) Integrate ZPLS with PSTN](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/optional-tasks/optional-integrate-zpls-with-pstn), Survivability route group and assignment. Checked 2026-10-01. [^61]: Site-level routing rules can be preserved during survivability by turning on Enable Routing Rules in the site's Zoom Node section. Source: [Configuring the Zoom Phone Local Survivability service](https://support.zoom.us/hc/en-us/articles/8427674303373-Configuring-Zoom-Phone-Local-Survivability-service-module), Routing rules. Checked 2026-10-01. [^62]: The SBC is added under the site's Settings > Routing > Session Border Controllers > Manage > Add, with its public IP and port, a Survivability public or private address and port, and In Service and Send OPTIONS ping turned on. Source: [ZPLS Field Guide - (Optional) Integrate ZPLS with PSTN](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/optional-tasks/optional-integrate-zpls-with-pstn), Add the SBC. Checked 2026-10-01. [^63]: Any SBC certified for Zoom Phone can be used with the ZPLS module, so customers already on a Zoom Phone BYOC plan need no separate SBC for survivability. Source: [PSTN Integration Considerations | Zoom Technical Library](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/before-you-begin/pstn-integration-considerations), PSTN integration - SBC. Checked 2026-10-01. [^64]: Customer SBCs must route inbound PSTN calls to the primary and secondary Zoom SIP zones before trying the ZPLS module. Source: [PSTN Integration Considerations | Zoom Technical Library](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/before-you-begin/pstn-integration-considerations), Call routing priority. Checked 2026-10-01. [^65]: Zoom's DigiCert root and intermediate certificates must be installed on the SBC for TLS connectivity with the ZPLS module. Source: [Configuring the Zoom Phone Local Survivability service](https://support.zoom.us/hc/en-us/articles/8427674303373-Configuring-Zoom-Phone-Local-Survivability-service-module), SBC / SIP trunk configuration. Checked 2026-10-01. [^66]: PSTN calling during survivability requires a customer-provided SBC connected either to a legacy connection or to a SIP trunk over a cellular or alternate connection. Source: [PSTN Integration Considerations | Zoom Technical Library](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/before-you-begin/pstn-integration-considerations), PSTN integration. Checked 2026-10-01. [^67]: An SBC used with ZPLS must support TLS 1.2, SRTP, mutual TLS, SIP, RFC 2833 DTMF, RFC 5853 topology hiding, mandatory SIP Early Offer, and the Opus, G.711 mu-law, G.711 A-law and G.729 codecs. Source: [PSTN Integration Considerations | Zoom Technical Library](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/before-you-begin/pstn-integration-considerations), SBC requirements. Checked 2026-10-01. [^68]: A Survivability Distribution Group is created under the site's Settings > Zoom Node > Survivable Distribution Group > Manage > Add and configured much like a call queue via Edit. Source: [ZPLS Field Guide - (Optional) Create a Survivability Distribution Group](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/optional-tasks/optional-create-a-survivability-distribution-group), Create a Survivability Distribution Group. Checked 2026-10-01. [^69]: An SDG that routes by phone number requires a configured BYOC PSTN integration. Source: [ZPLS Field Guide - (Optional) Create a Survivability Distribution Group](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/optional-tasks/optional-create-a-survivability-distribution-group), Prerequisite note. Checked 2026-10-01. [^70]: In survivability, calls to an auto receptionist, call queue or shared line group can be forwarded to a Survivable Distribution Group. Source: [Getting started with Zoom Phone Local Survivability service](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0058798), Supported features during survivability. Checked 2026-10-01. [^71]: ZPLS configuration option 1 (8 CPU, 16 GB RAM) supports 2,000 total registrations, 240 concurrent calls, 2 calls per second and 60 registrations per second. Source: [ZPLS Field Guide - Hardware Deployment Considerations](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/before-you-begin/hardware-deployment-considerations), Hardware Deployment Considerations - configuration option 1. Checked 2026-10-01. [^72]: ZPLS configuration option 2 (16 CPU, 16 GB RAM) supports 5,000 total registrations, 480 concurrent calls, 4 calls per second and 400 registrations per second. Source: [ZPLS Field Guide - Hardware Deployment Considerations](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/before-you-begin/hardware-deployment-considerations), Hardware Deployment Considerations - configuration option 2. Checked 2026-10-01. [^73]: An assigned ZPLS module is started by selecting it on the Zoom Node Services tab and clicking Start; allow at least 3 minutes for the status to change from Stopped to Running. Source: [ZPLS Field Guide - Initialize the ZPLS Module](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/initialize-the-zpls-module), Initialize the ZPLS Module - steps and timing note. Checked 2026-10-01. [^74]: The Zoom Node VM for ZPLS needs a static internal IPv4 address, and direct access to the appliance is available only through the virtual console. Source: [ZPLS Field Guide - Deploy the ZPLS Module](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/deploy-the-zpls-module), Deploy the ZPLS Module - network configuration. Checked 2026-10-01. [^75]: Survivability site assignments are static, so users who roam to another location during an outage are not covered by that location's module. Source: [Getting started with Zoom Phone Local Survivability service](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0058798), Limitations / considerations. Checked 2026-10-01. [^76]: Adding an SBC in the portal does not create the SIP trunk to ZPLS; the SBC must belong to a Survivability route group that is associated with the site or account. Source: [Configuring the Zoom Phone Local Survivability service](https://support.zoom.us/hc/en-us/articles/8427674303373-Configuring-Zoom-Phone-Local-Survivability-service-module), SBC / SIP trunk configuration. Checked 2026-10-01. [^77]: Site changes, including added or modified users and devices, are synchronised to the ZPLS module once every 10 hours. Source: [Zoom Phone Local Survivability | Zoom Technical Library](https://library.zoom.com/advanced-enterprise-services/zoom-node/zoom-node-explainer/zoom-phone-local-survivability), Configuration synchronisation. Checked 2026-10-01. [^78]: A full failover test blocks all connections to the Zoom Phone network, then confirms on the client (Settings > Statistics > Phone tab) that the Register Server IP and port match the ZPLS module, then restores connectivity. Source: [ZPLS Field Guide - Troubleshooting](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/troubleshooting), Simulating a failover. Checked 2026-10-01. [^79]: Testing Mode simulates failover without a real outage: after a module restart the module accepts new registrations from desktop clients whose users sign out and back in; IP phones and existing registrations are unaffected. Source: [ZPLS Field Guide - Troubleshooting](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/troubleshooting), Testing Mode. Checked 2026-10-01. [^80]: The ZPLS field guide states that only thick provisioning is supported for production deployments of the Zoom Node VM (disputed). Source: [ZPLS Field Guide - Deploy the ZPLS Module](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/deploy-the-zpls-module), Deploy the ZPLS Module - VM deployment from OVA. Checked 2026-10-01. [^81]: The ZPLS system requirements article describes thick provisioning (pre-allocation) as recommended rather than required (disputed). Source: [System requirements for the Zoom Phone Local Survivability service](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0060830), Disk / storage requirement note. Checked 2026-10-01. [^82]: ZPLS is the third-priority registrar for supported devices, after the primary and secondary cloud SIP zones; during normal operation it does not handle calls and sends OPTIONS pings to the site's SIP zones. Source: [Zoom Phone Local Survivability | Zoom Technical Library](https://library.zoom.com/advanced-enterprise-services/zoom-node/zoom-node-explainer/zoom-phone-local-survivability), How ZPLS works. Checked 2026-10-01. [^83]: Once the route group is assigned, the ZPLS module tries to establish a TLS connection with the SBC, and OPTIONS pings, if enabled, verify ongoing connectivity. Source: [ZPLS Field Guide - (Optional) Integrate ZPLS with PSTN](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/optional-tasks/optional-integrate-zpls-with-pstn), What to check after configuration. Checked 2026-10-01. [^84]: An operational module shows as Running, with its current version and IP address, under the site's Settings tab > Zoom Node > Local Survivability > Manage. Source: [ZPLS Field Guide - Confirm the ZPLS Module is Operational](https://library.zoom.com/zoom-workplace/zoom-phone/zoom-phone-local-survivability-field-guide/confirm-the-zpls-module-is-operational), Confirm the ZPLS Module is Operational. Checked 2026-10-01.