No Audio in voicemail

I am experiencing a very strange problem.
I dont seem to get any audio within the voicemail system.
I can call between extensions and out to pstn fine with audio and everything is ok. However when I try and access voicemail or when a call rings off and goes to voicemail I get messages in the asterisk cli saying it is playing vm-login but the phone is silent.

I also get the same thing with meetme rooms. When I enter an empty room the cli says its playing onlyperson but again get nothing.

Any ideas??

This is really doing my head in.


what asterisk version do you use?

what phones?