The SIP undelivered call notification feature provides a notification about the undelivered call to the endpoint. The endpoint logs this entry in the missed call log.

Communication Manager enables the undelivered call notification and sends the notification to Session Manager. Session Manager forwards the notification to the endpoint, and the endpoint logs the entry in the missed call log.

This feature has the following requirements:

• Communication Manager Release 6.3.6 or later

• Session Manager Release 6.3.8 or later

• 96x1 SIP endpoints Release 6.4 and later or Avaya one-X® Communicator for Windows SIP endpoints Release 6.2 or later.

This feature does not require any administration on Communication Manager or Session Manager and is available to the users by default. However, the Enable Layer 3 test field must be set to y on the signaling group between Communication Manager and Session Manager so that Communication Manager can understand the capabilities of Session Manager.

Communication Manager sends the undelivered call notification when a call is made directly to an endpoint but is not delivered to it. The following features trigger this notification:

• All call appearances are busy.

• Limit Number of Concurrent Call is activated and the endpoint is busy.

• Call Forward Busy or Call Forward All is enabled.

• Enhanced Call Forward (ECF) unconditional or ECF busy is enabled.

• Cover All Calls is enabled.