We're using a 3rd party SIP proxy to terminate some 3rd party SIP trunks. We have a SIP trunk between that proxy and CUCM. In addition, we have multiple gateways on our network that terminate PRI's.
I want to use the SIP trunks for outbound LD dialing and roll over to the PRI's when all SIP channels are full or down. For testing, we have 1 SIP channel to a 3rd party provider. If I place a call all works fine through the SIP trunk. When I place a second simultaneous call, I get a busy signal from the SIP proxy. I want CUCM to rollover to a PRI rather than just ring busy.
I have tried adding a PRI in the route list, tried adding a PRI-only route list to the route list group and have also tried adding a second LD (PRI) partition below the SIP partition in the CSS. I have not been able to get CUCM to roll over to our PRI's when the SIP channels are busy/down.
Any thoughts on how to accomplish this? Are we going to have to implement a gatekeeper?