We upgraded our CUCM environment from 10.5.2 to 12.5.1 recently and immediately faced what TAC is investigating as a potential bug. Our situation is we have SIP trunks to the PSTN that include MTP. Our integration with Unity Connection is SCCP. After the upgrade to CUCM 12.5, we no longer were getting DTMF into Unity Connection. We aren't the only ones that are experiencing the issue. TAC is investigating it and I don't see any bug yet that's been posted about it.
To get around the issue, they suggested we move our CUC integration to SIP instead of SCCP. We did that and the DTMF started to work.... BUT a feature I have been using since about 2001 stopped working. We setup voice mail profiles in CUCM to tie lines to specific voice mail boxes. That has the benefit of sending callers to specific voice mail boxes when they call a particular DN. It also makes it easy to retrieve voice mail from a particular box from a particular line on the phone. For example, we setup a second line a phone that goes into a hunt group (which, if not answered go to a shared voice mail box). With the old configuration those that wanted to retrieve voice mail from that box would press that line appearance on the phone, then press the voice mail button, enter the PIN and they can listen to the voice mail. That doesn't work with SIP integration. I had to enter alternate extensions in Unity Connection (which is limited to 9 extensions) to get the same functionality. NOT a very clean way to solve the problem, especially because for some of these we would need many more than 9 alternate extensions.
I am hoping that the SCCP integration with CUC is fixed soon.
