I feel your pain on this one my friend...
There are so many reason why a call can get "stuck." If this is a chronic, business impacting problem, I suggest opening a TAC case to have your logs reviewed.
Otherwise, search the forums for other threads relating to this topic.
Do you know if the call was active? What I mean is, was there a caller on the line for 45 minutes? I doubt it, as most people will not wait 45 minutes.
There has been a long standing issue with phantom calls in UCCX, and in 7x Cisco provided a way to clear these calls without the need for bouncing the whole CRS engine. So it's just something you learn to live with.
I would encourage you, if you don't already, limit the length of time a caller can queue, before you send them somewhere else. Or, put some sort of notification in place (email, place call, etc) so you can address the issue, before it becomes a 45 minute call, followed by a disconnect.
