[Asterisk-Users] ChanIsAvail and SIP

[Philipp von Klitzing]

Hi!

> > Hello all.  Has anyone had any success using ChanIsAvail with only SIP 
> > channels?  Is there another, better way to check if an extension is busy 
> > without dialing it?
> 
> Well, SIP devices live their own life and should really handle this signalling
> themselves. That's why ChanIsAvail does not really work with SIP channels,
> Asterisk does not control what is happening out there in the wild.

With the Manager API you have lots of options - probably "ExtensionState" 
could be one way for you to get closer to a solution.

An easier solution might be to employ AGI and use "CHANNEL STATUS 
[<channelname>]", provided this works with SIP and not only Zap (I just 
don't know). 

But first you'd need to find out about the channel name though since SIP 
channels have this random numbering: A "show channels" or "sip show 
inuse" at the CLI can provide that, and you can issue those commands also 
remotely from any script using "asterisk -rx <command>" and parse the 
result.

You could also use "database show SIP/Registry" on the CLI to see who is 
registered and who is not before attempting to place a call.

I probably missed a million other ways (that could include your own 
little SIP protocol query sent to the desired destination, for example). 
Just keep in mind that the SIP client can be busy even though for 
Asterisk it is not.

Cheers, Philipp