When using a 2-button phone like the 7941 the first button will be the Primary Line and the second button will be the Intercom. If the Managers primary line is 5555 and the Assistants primary line is 5001 - 5001 will be the "Proxy Line" for 5555. Have a look at this excellent doc;
IPMA with Proxy Line Support Interactive Voice Network Configuration Example
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...