I would like to use the CUE AA for some DNs but Exchange UM for voicemail on other DNs. Using PSTN SIP trunks I can get phone DNs that are configured for CFNA and CFB to transfer incoming PSTN calls to the AA but I can't get the PSTN calls to the Exchange UM. Calls from internal SCCP phones to Exchange work. Its only the PSTN calls that are being forwared to Exchange that don't go.
I read that to get calls from SIP trunks to CUE and Exchange I would need to setup call hairpining. I believe I have done this correctly since I can get the calls to CUE. Here is what I have found using ccsip debugs.
When a internal phone calls Exchange I see a SIP invite go to the Exchange IP on port 5060. Exchange then sends a 302 asking the call to go to 5065 the CME sends a second invite to port 5065 and the call connects.
When a PSTN call comes in to a phone/DN and is CFNOAN to Exchange I see a SIP invite to Exchange on TCP port 5060. Exchange then sends a 302 command telling the caller to go to port 5065. The call continues to go to port 5060, ignoring the 302 command to move to 5065.
If I can get the PSTN forwarded call to respect the 302 and send the invite to 5065 I believe this would solve my problem but I can't seem to find a way to do that.