Sip channel is not deleted

Hi,

have a problem with sip channels. When agent logoff without hangup his current call sip channel is not deleted. Need restart asterisk to clear it. Any idea how to fix it?
My asterisk version is 1.4.18

Error is fully repeatable - every time i test it it happen.

Greetings

Are you saying that he loggs off when he is on the phone with a caller ?

Yeah, when agent close application or is disconected from network asterisk show in console something like Unregistered SIP ‘AGENT112’ but sip channel is still there

I am not sure of the exact set up but the phone its self is still registered to asterisk so the call is still there. Unregistering will tell asterisk to just not send any more calls from what I understand.