[asterisk-dev] Call priority and Dial()

[Andrew Kohlsmith]

I forgot to mention what I was planning on adding to app_dial.  :-)

What I'm suggesting is adding a "call priority" field to ast_channel.  This 
field would default to a value of -1 (no priority), and the dial flag R(x) 
would be added to app_dial, which would set the priority for the new call leg 
to 'x'.

If app_dial cannot locate a free channel in its list of technologies to dial 
out of, it would search the list in exactly the same order that it does now, 
this time looking for the first channel that has a lower priority than 'x'.  
The first matching channel would then be soft hung-up, and Dial() would do 
its normal job using this newly freed channel.  If no channels with a lower 
priority than 'x' are found, Dial() would return CHANUNAVAIL or CONGESTION as 
usual.

I can already see someone wanting the option of playing a sound file to the 
channel (and its bridge peer) before hanging up, and a delay would also be 
required for analog (and some digital) Zaptel channels to allow this to work 
correctly.

Further, I can see people wanting to be able to set a default priority for a 
given channel technology, so hooks in the various technology-specific files 
may be a good idea (defaultprio=5 or something).  This is all blowing up the 
original scope significantly though; I'm not suggesting doing all of this at 
once, but rather only being aware that it may be desired and not coding so 
tightly that it becomes problematic later.

-A.