Site survivability for Webex Calling

Publisher

Cisco Systems, Inc. (help.webex.com)

URL

https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling

Published

2026-07-06

Updated

unknown

Accessed

2026-09-16

HTTP status

200

License

Cisco proprietary documentation, all rights reserved; no-redistribution; short excerpts and locators only

Source notes citing this source

• When the connection to Webex breaks, Webex Calling endpoints switch to Survivability mode, register with the local Survivability Gateway and keep internal, PSTN and emergency calling. in context
• Cisco recommends no more than 50 ms latency between a Webex Calling Survivability Gateway and the endpoints it serves when those endpoints are at multiple locations. in context
• Since Survivability Gateway is provisioned through Control Hub managed-gateway enrollment and controller-mode gateways cannot enrol, a gateway in SD-WAN controller mode probably cannot act as a Webex Calling Survivability Gateway. No source states this directly. inferred in context
• Webex Calling Survivability Gateway is available from Cisco IOS XE Dublin 17.12.3, and gateways are provisioned for it by enrolling them as Cisco IOS managed gateways in Control Hub and assigning the service. in context
• Webex Calling registrations and call control revert from the Survivability Gateway to the Webex cloud once the Webex connection has been restored for at least 30 seconds. in context
• The Webex Calling Survivability Gateway requires Cisco IOS XE Dublin 17.12.3 or later and must use an IPv4 address, because IPv6 is not supported. in context
• For Webex Calling, the Survivability Gateway is enabled with mode webex-sgw under voice register global, and the Webex cloud includes the gateway address, hostname and port in the device configuration instead of relying on a Unified CM SRST reference. in context
• On the Webex Calling Survivability Gateway, hunt groups, call forwarding and the basic auto attendant need IOS XE 17.18.2 or later. in context
• Catalyst 8200 and 8300 Edge models acting as Webex Calling Survivability Gateways support up to 2500 endpoint registrations. in context
• Emergency calling from a Webex Calling Survivability Gateway needs a PSTN circuit or SIP trunk and uses ELINs mapped by subnet to Emergency Response Locations. in context
• When one Survivability Gateway serves several physical locations, Enterprise Significant Numbers must be unique across those locations. in context
• After an outage, registrations and call control go back to the Webex cloud only once the Webex network connection has been restored for at least 30 seconds. in context
• The Webex Calling Survivability Gateway supports up to 100 hunt groups with at most 32 users in each group. in context
• The Webex Calling Survivability Gateway must use an IPv4 address; IPv6 is not supported. in context
• An ISR 4321 acting as a Webex Calling Survivability Gateway supports a maximum of 50 endpoint registrations. in context
• In a multi-location Survivability Gateway setup, Cisco recommends keeping latency between the Survivability Gateway and its endpoints at 50 ms or less. in context
• Webex Calling Survivability Gateway features require Cisco IOS XE Dublin 17.12.3 or later. in context
• Conferencing and three-way calling are not supported while a Webex Calling site is in survivability mode. in context
• In Webex Calling survivability mode the Park, Unpark, Barge, Pickup, Group Pickup and Call Pull softkeys are not supported. in context
• Each site that deploys Webex Calling Site Survivability needs a Survivability Gateway inside that site's local network. in context
• During an outage, PSTN service at a Webex Calling survivability site works only through SIP trunks or PSTN circuits that stay reachable. The gateway reaches the PSTN through a voice interface card or a SIP trunk to a PSTN gateway. in context
• The Webex Calling Survivability Gateway accepts only certificates from publicly known CAs; private or enterprise CA certificates cannot be used. in context
• The Webex Calling Survivability Gateway provides backup calling when a site loses its connection to the Webex cloud: endpoints register locally and keep intrasite calling, PSTN calling and emergency calling. in context
• The Survivability Gateway syncs user authentication and routing data from Webex daily, and an on-demand sync status update in Control Hub can take up to 30 minutes. in context
• For survivability, the Webex App on Windows and Mac must be at least version 43.2. in context
• During survivability, outbound emergency calls from Webex Calling endpoints use a registered ELIN for a defined ERL, and callbacks to that ELIN are directed to the last device that called the emergency number. in context
• Failback from the Webex Calling Survivability Gateway to the cloud is automatic once the Webex connection has been restored for 30 seconds or more. in context
• The Webex Calling Survivability Gateway takes over SIP registration for endpoints when the connection to Webex has been broken for more than 30 seconds. in context
• The IOS XE releases where the SRST guide says the Webex Survivability Gateway was introduced (17.9.x and 17.11.1a) sit below the 17.12.3 minimum in the current Webex help article, so a new deployment should plan to the help article's floor rather than the introduction release. inferred in context
• Hunt group, call forward and auto attendant support on the Webex Calling Survivability Gateway requires IOS XE 17.18.2 or later. in context
• In Webex Calling survivability mode, hunt groups are limited to 100 groups with at most 32 users per group. in context
• The Webex Calling Survivability Gateway supports IPv4 only, and Cisco recommends no more than 50 ms latency across a multi-location LAN served by one gateway. in context
• The current Webex Calling Site Survivability article lists Cisco IOS XE Dublin 17.12.3 as the minimum release for a Survivability Gateway. in context
• Supported Survivability Gateway platforms are ISR 4000 series, Catalyst 8200 and 8300 Edge and Catalyst 8000V; endpoint capacity ranges from 50 on an ISR 4321 to 2,500 on a Catalyst 8300. in context
• Webex Calling Site Survivability uses a Cisco IOS XE router on the customer network, called the Survivability Gateway, to provide fallback calling to on-site endpoints when connectivity to the Webex cloud is lost. in context
• Webex Calling survivability mode does not support three-way calling, conferencing, park, barge, pickup, remote line-state monitoring or the calling dock. in context
• Basic Automatic Call Distribution is not supported where the Survivability Gateway and the Local Gateway are colocated on one device. in context
• In Survivability mode calls are stored locally in the call history on both MPP devices and the Webex App, and Cisco states that dialing patterns could work differently in Survivability mode than in Active mode. in context
• Cisco states that devices with 4G and 5G connectivity, for example the Webex App on a mobile or tablet, could still register to Webex Calling during an outage and as a result could be unable to call other numbers from the same site location. in context
• One gateway can carry both a Webex Survivability configuration and a Unified SRST configuration, providing survivability for Webex Calling endpoints and for endpoints registered to Unified Communications Manager, and the Survivability Gateway routes internal calls automatically between any registered clients whether they arrived by SRST or by Webex Calling. in context
• The Survivability Gateway syncs calling information daily from the Webex cloud for the endpoints at its location, and that sync carries both authentication information, so endpoints keep secure registrations while in Survivability mode, and routing information, so the gateway can route internal calls automatically. in context
• E911 calling in Survivability mode requires a PSTN circuit or SIP trunk, outbound emergency calls use a specific registered Emergency Location Identification Number for a defined Emergency Response Location, and if the emergency operator returns a disconnected call the Survivability Gateway directs it to the last device that called the emergency number. in context
• Site survivability requires minimum endpoint software of 12.0(1) on Cisco MPP phones and on the 7832 and 8832 conference phones, Phone OS 3.2 or later on the 8875, PhoneOS 3.2(1) on the Desk Phone 9800 series, Webex App 43.2, 17.16.1a on the VG400 VG410 and VG420 adapters and 11.3(1) on the ATA 191 and 192. in context
• The Webex cloud places the Survivability Gateway's IP address, hostname and port in the endpoint's device configuration file, which is how an endpoint knows where to register when the connection to Webex breaks. in context
• Webex Calling Survivability Gateway features require Cisco IOS XE Dublin 17.12.3 or later, and the hunt group, call forward and auto attendant features require IOS 17.18.2 or later. in context
• In Survivability mode up to 100 hunt groups can be configured with a maximum of 32 users each, the weighted call routing pattern is not supported, and the supported hunt group patterns are sequential, parallel, peer and longest-idle. in context
• The Survivability Gateway must use an IPv4 address and IPv6 is not supported, and an on-demand sync status update in Control Hub could take up to 30 minutes. in context
• Where several smaller locations in one LAN are mapped to a single Survivability Gateway, Cisco recommends maintaining a latency threshold of 50 milliseconds for connectivity between the gateway and endpoints across those locations. in context
• Third party devices are not supported with the Survivability Gateway, and the supported endpoint table names Cisco MPP phones, the Cisco Desk Phone 9800 series, the 7832 and 8832 conference phones, the Webex App on Windows and Mac, and the VG400 VG410 VG420 and ATA 191 and 192 analog endpoints. in context
• Cisco publishes maximum endpoint registrations for 15 Survivability Gateway platforms, running from 50 on an Integrated Services Router 4321 to 2000 on the 4451-X and 4461 and 2500 on the Catalyst Edge 8200-1N-4T and the four Catalyst Edge 8300 models, with the Catalyst Edge 8000V software configurations at 500, 1000 and 2000. in context
• In Survivability mode calls to a shared line can ring on all devices, while remote line state monitoring, hold, resume, synchronized do not disturb and call forwarding settings are not available on that shared line. in context
• Cisco states that the SIP bind command must not be configured in voice service voip configuration mode on a Survivability Gateway because it leads to registration failure of endpoints with the gateway. in context
• In Survivability mode the MPP softkeys Park, Unpark, Barge, Pickup, Group Pickup and Call Pull are not supported, and Cisco states that they do not appear disabled on the device. in context
• In Survivability mode on MPP devices and the Webex App, attended call transfer and blind call transfer are both supported while conferencing and three-way calling are not, and on VG4xx analog terminal adapters transfer is supported only when the incoming call is received on the adapter. in context
• Webex Calling endpoints run in Active mode registered to the Webex cloud by default, switch automatically to Survivability mode and register with a local Survivability Gateway when the connection to Webex is lost, and revert to the cloud for both registration and call control once the Webex connection resumes for at least 30 seconds. in context

Cite this source record

APA

WarmTransfer. (2026, July 6). Site survivability for Webex Calling. WarmTransfer. https://warmtransfer.net/knowledge/sources/cisco-help-d68vi1-site-survivability

BibTeX

@misc{warmtransfer-cisco-help-d68vi1-site-survivability,
  title  = {Site survivability for Webex Calling},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/sources/cisco-help-d68vi1-site-survivability},
  note   = {Cisco Systems, Inc. (help.webex.com), accessed 2026-09-16}
}