[Asterisk-Dev] PROGRESS messages with Cause 17 (User Busy) - Bug # 4250

[Clint Guillot]

Bug #4250 (http://bugs.digium.com/view.php?id=4250) describes a 
situation in which an outbound call via a PRI hangs in limbo forever 
due to a seemingly malformed Q.931 response.

Another bug, #4347, has recently been opened describing the same 
problem.

There has been some discussion re: this situation and multiple parties 
have proposed patches to cause asterisk to behave properly in spite of 
the observed behavior from the switch.

However, there has been no discussion of the original question, 
therefore I pose it here:

Is it a violation of Q.931 for a PROGRESS message to contain a cause 
code 17 (User busy), AND for this to be the only indication that a call 
has failed with a busy condition?
Is a HANGUP message not required in this instance?

See Bug #4250 (http://bugs.digium.com/view.php?id=4250) for a PRI debug 
span log of this situation occuring.

A patch to work around provider brokenness is great, proving to the 
provider that they have a problem and making them fix it is Better(tm).


Thanks all,
Clint