Orphaned Channels

How do you hang up a SIP channel that has been orphaned. I know that you can request a channel to be hung up by using soft hangup “channel name”. That will only work if the next time that channel gets read or written too, but in the case of an orphan that won’t happen.

The problem I’ve got is that I have an open SIP channel to the voicemail app.
SIP/0004f216a2b6-b6a s@macro-accessMailbo Up VoiceMailMain(212@xxxx)

Since the channel won’t hang up the hints show the state in use which is false. So the receptionist phone doesn’t know if that extension is actually in use. Any idea how to deal with this besides restarting asterisk?