[Asterisk-Dev] why does priindication_oob default to 0?

[Peter Svensson]

On Sat, 8 Jan 2005, Andrew Kohlsmith wrote:

> I posted this as a bug (3287) but mark closed it immediately -- I'd posted 
> there to get his input since he doesn't seem to frequent the list often and 
> wasn't on IRC.  Oh well, let's try here instead.
> 
> Mark's answer was that it defaults to 'inband' for backward compatibility -- 
> Ok, but why are we defaulting to accomodate the weird PRI indication state 
> instead of defaulting to the most common and allowing the indication to be 
> set to inband to accomodate for the weird PRIs out there?

>From what I can tell the priindication affects the sending of "busy" and 
"congestion" indications from the corresponding applications. With the 
inband method selected these applications behave like they do for 
non-isdn, i.e. they play a sound and wait for a timeout or for the other 
end to hangup. If a timeout is specified and passes control continues in 
the dialplan and you can e.g. say something.

With out of band selected they immediatly send a RELEASE message with the
corresponding cause code set. The line is immediatly cut off and 
someone in the path close to the caller is responsible for generating the 
audio feedback. 

The immediate release effect can be created even if the inband method is 
selected, if desired, by setting PRI_CAUSE and calling hangup. A quite 
common use is to call Busy(10) on the unanswered line and then hanging up 
(the still unanswered line) with PRI_CAUSE set suitably. This handles all 
weird remote cases.

I guess defaulting to "inband" may be seen as the least surprising default 
behaviour for the two applications "Busy" and "Congestion" since they will 
behave similarly for isdn and non-isdn lines.

Peter