The following procedure and settings refer to the trunk groups that are used only for SIP signaling to the SIP agent deskphones.
Procedure
In the Group Type field, select SIP.
In the Signaling Group field, assign the number of the signaling group defined on the Signaling Group screen.
In the Number of Members field, assign the number of 96X1 SIP phones that the trunk must support. Communication Manager automatically assigns the IP port numbers.
In the Redirect on OPTIM Failure (ROOF) field, enter 5000 (5 seconds).
In the Preferred Minimum Session Refresh Interval (sec) field, assign a value from 90 to 64800. The default setting is 600. To prevent spikes in the processor occupancy, assign a value that is greater than the sum of the average call handling time and the average call queuing time. For example, if the average call queuing time is 3 minutes and the average call handling time is 10 minutes, assign a field value that is greater than 780 seconds.
Note:
Although Communication Manager uses the configured value for outbound calls when the traffic is relatively low, during peak traffic conditions Communication Manager increases the session refresh interval value dynamically for protection against the processor occupancy spikes.
If the service provider network for SIP uses a session refresh interval value that is higher than the configured value for Preferred Minimum Session Refresh Interval but relatively low compared to the amount of SIP traffic that Communication Manager currently handles, Communication Manager rejects the calls with a 4xx response and includes the suggested session refresh interval value for call attempt. Therefore, large call centers must ensure that the service provider network uses a session refresh interval value that is greater than 1800 seconds within the INVITE message to ensure that Communication Manager accepts calls in the first attempt, regardless of the SIP call traffic load that Communication Manager might be handling.
In the Measured field, select none for the signaling trunks to Session Manager.
In the Numbering Format field, select private, which is the default for SIP.
In the Show ANSWERED BY on Display field, select y.
In the Support Request History field on the Protocol Variations page, select y. If the field setting is n, the SIP agent deskphone displays do not function correctly.
