[asterisk-users] Can I emulate SIP presence for an extension?

[Ade Vickers]

I wrote:
 
> So, is there any way of monitoring the status of a device on 
> a "remote"
> server, perhaps utilising an IAX2 channel?

To answer my own question, I did it :)

In case anyone's remotely interested in a similar setup/idea, here's the
relevant bits of my dialplan.

Assume that a call, having been answered, now needs dumping in the
"telemarketer tarpit of death"....

Up in default, I have the following defined:

	exten => 5555,hint,custom:telepark

So, that sets up the custom:telepark "device", which will be either busy or
idle.

On serverA (local), I have this extension defined:

	;Death to telemarketers
	exten => 5555,1,Goto,teledeath|s|1

That jumps into the teledeath context, defined as:

	[teledeath]
	exten => s,1,Answer()
	exten => s,2,Set(DEVSTATE(Custom:telepark)=INUSE)
	exten => s,3,Dial(IAX2/serverC/teledeath_on)
	exten => s,4,WaitMusicOnHold(15)
	exten => s,5,Wait(1.5)
	exten => s,6,Playback(pls-hold-while-try)
	exten => s,7,Wait(0.25)
	exten => s,8,Goto,4

	exten => h,1,Set(DEVSTATE(Custom:telepark)=NOT_INUSE)
	exten => h,n,Dial(IAX2/serverC/teledeath_off)
	exten => h,n,Hangup()

Step 2 sets the custom:telepark to be in use (lighting the lamp on anything
connected to serverA(local) which is watching extension 5555).
Step 3 calls the extension teledeath_on on the remote server (serverC)
Steps 4-8 keep the telemarketer busy...

When they finally give up, exten h is called: 
Step 1 simply re-sets the device state
Step 2 calls extension teledeath_off on the remote server

Meanwhile, on my remote server, I simply define a SIP hint:

	exten => 5555,hint,Custom:teledeath

and two extensions:

	;Death to telemarketers status marker
	exten => teledeath_on,1,Set(DEVSTATE(Custom:teledeath)=INUSE)
	exten => teledeath_on,n,Set(HANGUPCAUSE=17)
	exten => teledeath_on,n,Hangup()

	exten => teledeath_off,1,Set(DEVSTATE(Custom:teledeath)=NOT_INUSE)
	exten => teledeath_off,n,Hangup()

Note that the middle step of teledeath_on is required to prevent the local
server from seeing a "caller hung up" event; which would otherwise cause the
music to stop & the telemarketer to be disconnected; which is not what we
want to happen...



The only problem with this scheme occurs if I do something stupid:

1) Dial 5555 from any of the connected phones (goes to teledeath loop)
2) Hit transfer, dial 5555 & send
3) Now I've got a call locked in the system, constantly trying to play music
to itself....

Any ideas on how I could prevent it doing that?


Cheers,
Ade.

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