The DN's are likely set up as dual-line DN's so you need to add the following (huntstop channel command).
Have a look;
The following example creates an ephone-dn with the number 103 in dual-line mode. The no huntstop command allows calls to continue to hunt to other ephone-dns if this one is busy or does not answer. The huntstop channel command disables call hunting to the second channel of this ephone-dn if the first channel is busy or does not answer.
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...