The SBC switches to the local survivable mode under the following conditions:

  • IP connection to the Application Server (AS) that hosts the registered subscriber is lost or AS is down. This is detected by using Address Reachability Service (ARS) through blacklisting algorithms such as timeouts to OPTIONS or INVITE requests.
  • AS is overloaded and cannot process calls or registrations.
  • The SBC detects overload mode using enhanced ARS service acting on AS responses with a retryAfter header for the SIP OOD requests.


To View and Edit Local Survivability

On the SBC main screen, go to ALL > Address Context > Zone >  Sip Trunk Group > Services > Local Survivability. The Local Survivability window is displayed.

Figure 1: Sip Trunk Advanced - Sip Trunk Group - Services - Advanced - Local Survivibility Parameters

The following fields are displayed:

Table 1: Sip Trunk Group - Services - Local Survivability

Parameter

Description

Local Survivability State

Enable this flag to activate local call routing. The SBC switches to local Survivable Mode if it is enabled.

The options include:

  • disabled (default)
  • enabled

Allow Local Registration

Enable this flag to allow local registration when the ARS blacklist the Application Server (AS).

  • If allowLocalRegistration configuration is enabled towards Access side, the SBC handles new registration requests locally.
  • If allowLocalRegistration configuration is enabled, the SBC accepts the registration request without authentication and locally respond with a 200OK.

The options include:

  • disabled
  • enabled

Make the required changes and click Save at the right hand bottom of the panel to save the changes made.