I have a customer running CUCM 7.1(2) who has two Cisco voice gateways each with one PRI and a Quescom GSM gateway with four SIMM cards allowing four calls. The Cisco voice gateways are configured as H.323 gateways and the Quescom GSM gateway is accessed as a non-gatekeeper inter-cluster trunk as recommended in the Quescom config guide which is attached to this post.
I have set up the dial plan such that calls to mobiles hit a route list with two route groups. The first route group contains the Quescom GSM gateway and the second route list contains the two Cisco PRI gateways.
My issue is that when all four channels on the Quescom gateway are in use and I attempt to place a fifth call I get an Annunciator message stating "Your call cannot be completed at this time". What I would like to happen is for the fifth and subsequent calls to be routed via the Cisco PRI gateways.
I have seen from the logs available on the Quescom unit that the fifth call to it is rejected with a Q.931 cause code of 22 - No circuit/channel available.
I have done some research and changed the values of the CUCM service parameters Stop Routing on Unallocated Number Flag and Stop Routing on User Busy Flag to false but this does not resolve the issue.
Can anyone suggest how this issue may be resolved.