it looks to be calls coming to the auto attd, the locked up links are either an outside call talking to a vmail port or an outgoing call from a vmail port to a speed dial that is an offsite phone number . doing a force busy on the peer and return to service doesn't clear them
they are using a device from lightpath called a siparator which doesn't require a registration it has an ip on the network and that is what the 3300 sends calls thru , a normal call that gets to an ext shows the bye and tears down the link when the ext goes on hook , they had a configuration for a 3300 that we followed I am trying to trap a call that locks up the link
this was a system with 3 working pri circuits they just ported incoming to sip , the sip trunks were used outgoing with no issue for a few months