Can you paste your router configs (all pots and voip dial peers). Default codec on voip dial peers is g729. Any reason for using that ? You can change it to g711ulaw or alaw using codec command. (Thought IP Phones should be able to negotiate the codec on the fly)
Are the gateway and IP phones in question in same device pool ?
Also check the location settings of the gateway and phones to make sure the locations have enough bandwidth. You may also try clicking the "Resynchronize bandwidth" button to gain back any unused bandwidth.
I'm not able to access my old voice mail messages all of a sudden. The recording says something like 'the message is currently not available'. This has never happened before in all the years I have been using this system. I have t...