# Webex Calling Site Survivability Gateway

Canonical: https://warmtransfer.net/knowledge/webex-calling-survivability-gateway

Last verified: 2026-09-24

Webex Calling endpoints register to the Webex cloud by default in Active mode and switch automatically to a local Survivability Gateway in Survivability mode when cloud connectivity is lost[^23]. When the Webex connection resumes for at least 30 seconds, endpoints revert both registration and call control to the cloud[^23].

## How it works

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[^12]. 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[^9]. An on-demand sync status update in Control Hub could take up to 30 minutes[^15].

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[^16]. 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[^7].

## Feature behavior and limitations

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[^22]. 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[^19]. 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[^21]. 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[^6].

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[^10].

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[^14].

## Gateway platform and software requirements

The Survivability Gateway must use an IPv4 address and IPv6 is not supported[^15]. 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[^20].

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[^8]. Basic Automatic Call Distribution is not supported where the Survivability Gateway and the Local Gateway are colocated on one device[^5].

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[^13]. Cisco publishes maximum endpoint registrations for 15 Survivability Gateway platforms[^18]:

| Platform | Endpoint Capacity |
| --- | --- |
| Integrated Services Router 4321 | 50[^18] |
| Catalyst Edge 8000V software configurations | 500, 1000 and 2000[^18] |
| Integrated Services Router 4451-X | 2000[^18] |
| 4461 | 2000[^18] |
| Catalyst Edge 8200-1N-4T | 2500[^18] |
| the four Catalyst Edge 8300 models | 2500[^18] |

## Supported endpoints and firmware

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[^17]. 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[^11]:

| Endpoint Family | Supported Devices | Minimum Version |
| --- | --- | --- |
| Cisco MPP phones | Cisco MPP phones[^17] | 12.0(1)[^11] |
| Conference phones | 7832 and 8832[^17] | 12.0(1)[^11] |
| Cisco Desk Phone 9800 series | Cisco Desk Phone 9800 series[^17] | PhoneOS 3.2(1)[^11] |
| 8875 | 8875[^11] | Phone OS 3.2 or later[^11] |
| Webex App | Windows and Mac[^17] | 43.2[^11] |
| Analog endpoints | VG400 VG410 VG420[^17] | 17.16.1a[^11] |
| Analog endpoints | ATA 191 and 192[^17] | 11.3(1)[^11] |

## See also

- See also [Local Gateway design and configuration](https://warmtransfer.net/knowledge/webex-calling-local-gateway).
- See also [Webex Calling enhanced emergency calling](https://warmtransfer.net/knowledge/webex-calling-emergency-calling).
- See also [Webex Calling supported devices and MPP firmware](https://warmtransfer.net/knowledge/webex-calling-device-support).
- See also [Webex Calling architecture and deployment models](https://warmtransfer.net/knowledge/webex-calling-architecture).

## Applicability

Applies to: Cisco Webex Calling. Sources checked 2026-09-16. 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[^13]. 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[^11].

## What remains uncertain

The Survivability Gateway port reference table this tranche did not extract is not covered by the sources below. Whether locally stored call history from an outage reaches the cloud afterwards is not covered by the sources below. How long an endpoint takes to decide Webex is unreachable and fail over is not covered by the sources below. Which dialing patterns behave differently in Survivability mode is not covered by the sources below. Whether the colocation article's guidance still holds is not covered by the sources below.

## Sources

[^1]: 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. Source: [Site survivability for Webex Calling](https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling), overview of Survivability mode and supported call types. Checked 2026-09-24.
[^2]: 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. Source: [Site survivability for Webex Calling](https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling), network requirements for Survivability Gateway (multi-location deployments). Checked 2026-09-24.
[^3]: The target architecture adds Webex Calling as the cloud call service, Cisco Directory Connector or the Entra ID wizard application for identity synchronisation, a Local Gateway for PSTN access and Unified CM interoperation, and a Survivability Gateway for fallback calling during outages; Cisco Calling Plan and Cloud Connect require no on-premises equipment. Source: [Transitioning from Unified CM to Webex Calling — Deployment Guide](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/mcp/DEPLOYMENT_CALLING_Unified_CM_to_Webex_Calling.pdf), Core components, Table 3. Checked 2026-09-04.
[^4]: Cisco states that Dedicated Instance customers have access to the Unified Communications Manager security features for endpoints and UC applications including encrypted media, secure Survivable Remote Site Telephony and secure over-the-top registration using Mobile and Remote Access, and to Survivable Remote Site Telephony for site connectivity when network links go down together with Emergency Responder and Nomadic E911. Source: [Introduction to Dedicated Instance](https://help.webex.com/en-us/article/dk3o5r/Introduction-to-Dedicated-Instance), Simple migration path, Uncompromised Security paragraph. Checked 2026-09-16.
[^5]: Basic Automatic Call Distribution is not supported where the Survivability Gateway and the Local Gateway are colocated on one device. Source: [Site survivability for Webex Calling](https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling), Limitations and restrictions, Basic Automatic Call Distribution (B-ACD). Checked 2026-09-16.
[^6]: 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. Source: [Site survivability for Webex Calling](https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling), Limitations and restrictions, Call History and third bullet. Checked 2026-09-16.
[^7]: 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. Source: [Site survivability for Webex Calling](https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling), Limitations and restrictions, second bullet. Checked 2026-09-16.
[^8]: 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. Source: [Site survivability for Webex Calling](https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling), Colocation with Unified SRST and Call routing considerations for colocation. Checked 2026-09-16.
[^9]: 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. Source: [Site survivability for Webex Calling](https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling), Deployment considerations, and Key conditions for Site Survivability bullets 2 and 3. Checked 2026-09-16.
[^10]: 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. Source: [Site survivability for Webex Calling](https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling), Supported features and components, Table 1 E911 Call Handling row. Checked 2026-09-16.
[^11]: 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. Source: [Site survivability for Webex Calling](https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling), Supported endpoint models, Table 2, Minimum Version column. Checked 2026-09-16.
[^12]: 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. Source: [Site survivability for Webex Calling](https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling), Key conditions for Site Survivability, first bullet. Checked 2026-09-16.
[^13]: 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. Source: [Site survivability for Webex Calling](https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling), Supported endpoint models, paragraph preceding Table 3. Checked 2026-09-16.
[^14]: 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. Source: [Site survivability for Webex Calling](https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling), Limitations and restrictions Hunt Groups and Hunt Group Call Routing; Table 1 Hunt Group row. Checked 2026-09-16.
[^15]: 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. Source: [Site survivability for Webex Calling](https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling), Limitations and restrictions, bullets 4 and 5. Checked 2026-09-16.
[^16]: 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. Source: [Site survivability for Webex Calling](https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling), Multi location set up, closing sentence. Checked 2026-09-16.
[^17]: 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. Source: [Site survivability for Webex Calling](https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling), Supported endpoint models, Table 2 and the note beneath it. Checked 2026-09-16.
[^18]: 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. Source: [Site survivability for Webex Calling](https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling), Supported platform models, Table 3, read as table cells. Checked 2026-09-16.
[^19]: 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. Source: [Site survivability for Webex Calling](https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling), Limitations and restrictions, Shared Lines. Checked 2026-09-16.
[^20]: 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. Source: [Site survivability for Webex Calling](https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling), Limitations and restrictions, sixth bullet. Checked 2026-09-16.
[^21]: 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. Source: [Site survivability for Webex Calling](https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling), Limitations and restrictions, MPP Softkeys. Checked 2026-09-16.
[^22]: 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. Source: [Site survivability for Webex Calling](https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling), Supported features and components, Table 1 rows Attended Call Transfer, Blind Call Transfer and Three-way Calling; and Limitations and restrictions, Conferencing. Checked 2026-09-16.
[^23]: 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. Source: [Site survivability for Webex Calling](https://help.webex.com/en-us/article/d68vi1/Site-Survivability-for-Webex-Calling), Deployment considerations, and Key conditions for Site Survivability final bullet. Checked 2026-09-16.