Detailed description of SIP Agent Reachability

Last Updated : Jul 27, 2020 |

The SIP Agent Reachability feature determines the availability of a SIP station. The SIP station acts as an agent for both Communication Manager and AES applications.

Session Manager maintains the registration state of a SIP station. However, the station might not be reachable from Communication Manager because of a network outage between the station and Session Manager or Avaya SBC, or a disruption between Communication Manager and Session Manager.

After you enable the SIP Agent Reachability feature, Communication Manager can detect the reachability status of a SIP station and takes actions as configured.

The feature works as follows:

Communication Manager checks the reachability status of idle agents and idle domain controlled SIP stations, if enabled by configuration. The frequency of the attempts is determined by the SIP Reachability Polling Interval field on the system-parameters-features form.

When a SIP station is unavailable, Communication Manager does the following:

  • SIP agent: When the first reachability attempt fails, Communication Manager puts the agent in the aux-work mode with the ROOF reason code. If the agent is already in aux-work mode with ROOF reason code, the agent decreases the reachability attempts, as administered in SIP Station Reachability Attempts by one. If the agent is already in aux-work mode, however with a different reason code, the agent is removed to aux-work with ROOF reason code.

  • Domain controlled station: Communication Manager should update the application by sending the Registered out-of-service message.

To differentiate between a temporary network disruption and a network outage, Communication Manager continues to make attempts in determining the reachability status of the stations. The number of additional attempts is determined by the value configured in the SIP Station Reachability Attempts field on the system-parameters-features form. If the station becomes reachable in any of the attempts, Communication Manager takes appropriate actions as follows:

  • SIP agent: The agent continues to remain in the aux-work mode. The station used by the agent is notified that it is in the aux-work mode.

  • Domain controlled station: No operation.

If all the attempts fail, Communication Manager declares the station unreachable and does the following:

  • SIP agent: Communication Manager logs out the agent with the reason code configured on Forced Agent Logout for Unreachable Reason Code on the system-parameters-feature form.

  • Domain controlled station: Communication Manager should update the application with Unregistered out-of-service message.

After the station is unreachable, Communication Manager continues to determine the reachability status of a station for the duration as configured in the SIP Unreachable Polling Period field on the system-parameters-features form. If Communication Manager determines that a station is reachable during the period, Communication Manager does the following:

  • SIP agent: Update the status of the station with the agent’s logged-off state.

  • Domain controlled SIP station: Communication Manager should update the Application with Unregistered out-of-service message.

Otherwise, after the duration is over, Communication Manager does the following:

  • SIP agent: Communication Manager stops determining the reachability status of the station.

  • Domain controlled SIP station: Communication Manager stops determining the reachability status of the station. Communication Manager resumes the action when the station logs in again.