I have a CME/CUE configured on a cisco 2811 Router. I have two offices that share this CME/CUE. Office 1 is in the same room as the 2811 router which has a FXO card with 3 analog phone in it. Users in Office 1 do not have any problems.
Office2 users have their own VOICE Gateway router (Cisco 1760)with an FXO card because they have their own phone lines, but their IP phones are configured on the CME in office1. When office2 users try to check their voicemails REMOTELY (like from a cell phone) they can hear the auto attendant perfectly, but when the message plays they CAN'T hear it and its all garbled, but if you listen to the message on the IP phone itself you can hear the message fine. I've had the phone lines tested and they are good. There are only two phone lines in office2.
Office 1 user don't have a problem at all when listening to their messages remotely.