This is a recent problem that affects internal calls between two locations. Until recently, calls dialed to the remote location that were forwarded to voice mail were directed to the recipient's CUE and in both directions. Now when those calls go to voice mail they are being directed to the originator's CUE, and, of course, can't be recognized.
Both systems do use the same extension for voice mail but that didn't seem to matter until now.
I did add multi-party ad-hoc and a meetme conference to the main system, with hardware conferencing, and I suspect that "broke" it but I'm not sure what part of that configuration could be at fault.
I doubt that it matters, but the main location is CME 4.3/7 CUE 3.2.1 and the remote is a UC500 CME 4.2(0) CUE 2.3.4
Hints, or suggestions, from experience will be appreciated.