Channel name is changing after going through queue agents

Asterisk 1.8.15

Issue: When a call is sent to a queue and all agents are rung, if no agent answers and confirms to accept the call on the first round of calls, all subsequent rounds of calls to agents result in an error after they confirm the call:

-- <SIP/BW-SIP-A-00003215> Playing 'custom/call_confirm_announcement.slin' (language 'en')

[2012-12-27 12:27:13] ERROR[25257]: func_global.c:154 shared_read: Channel ‘SIP/2015-00003208’ not found! Variable ‘ANSWER_STATUS’ will be blank.

Agent is then played the ‘call already taken’ message.

It seems to me that the channel is being renamed when going back through the queue. Has anyone else seen this?

I have run into the same problem, how did you resolve this?

I am not sure what the underlying problem is, i am sure it is something simple that I don’t understand.

For reference if anyone reads this old thread and has the same problem.

Turn on a join announcement for the inbound call, I dont understand why this fixes it but it resolved my problem.

If anyone can explain why this fixes it that would be real appreciated