Ralph,
When I test the multicall directly I get a message saying it is no longer in service which is very strange.
I went to the maintenance and for one of the phones that don't ring using the LOc ext <ext> command I do get the plid but, when I try the stat mls <plid> command I get an error.  I tried it with both with the numbers seperated and together.  So basically, stat mls 1 3 1 50 1.  It says: The command text as entered is incomplete.
I also was able to look at the status  of multicall and it is not busy or holding.