[Asterisk-Users] 911 context, is this right?

[Rich Adamson]

> I have 3 analog trunks zap/1, zap/4 and zap/5.  zap/5 is the least used
> line.  Would the following work for 911 calls?
> 
> [e911]
> exten => 911,1,ChanIsAvail(Zap/1)
> exten => 911,2,Dial(Zap/1/911)
> exten => 911,3,Hangup()
> exten => 911,102,ChanIsAvail(Zap/4)   
> exten => 911,103,Dial(Zap/4/911)
> exten => 911,104,Hangup()
> exten => 911,203,ChanIsAvail(Zap/5)
> exten => 911,204,Dial(Zap/5/911)
> exten => 911,205,Hangup()
> exten => 911,304,SoftHangup(Zap/5-1)
> exten => 911,305,Wait(2)
> exten => 911,306,Goto(204)
> 
> Did I get the Priority + 101 idea right here?

Probably a better way to do that is to use "group=17" within the
zapata.conf definitions for zap/1, zap/4, and zap/5. Then use 
something like 
 exten => 911,1,Dial(Zap/g17/${EXTEN})

In your example above, if ChanIsAvail(Zap/1) finds that Zap/1 is
unavailable, then priority 102 will be executed. However, what do
you want to happen if Zap/1 is available (at least from asterisk's
perspective), but the pstn line on Zap/1 doesn't process the call
for whatever reason?

If you're doing the above for a home system, you can probably handle
failures in lots of different ways. But, if you're doing this for
a business client, the above approach will leave you open for a
fair number of legal liability issues when it doesn't work as 
expected.

Just as a simple test, disconnect the pstn line from Zap/1 and
see what happens when a call is placed.