[Asterisk-Users] Picking an open channel (FXO port) for outbound calls

[Tony Kava]

Greetings:

I did some quick searching of my history of this list, and I tried a quick
Google search as well, but perhaps someone on the list can quickly answer
this question.  I have a very nicely working Asterisk system at home with
two Digium X100P FXO cards.  When my SIP phones want to dial-out I have them
setup to grab the first analog card (Zap/1) with the following
extensions.conf segment:

==== snippet ====

; Outbound
exten => _9.,1,Dial(Zap/1/${EXTEN:1},90,Tt)
exten => _9.,2,Macro(fastbusy)
exten => _9.,102,Macro(fastbusy)

==== /snippet ====

Zap/1 and Zap/2 are analog phone lines.  What is the best method of picking
an open line when someone tries to dial-out? i.e. if Zap/1 is in use how can
I instruct Asterisk to use Zap/2 and vice versa? I know complex methods of
making this happen, but I'm sure there is a very simple way to accomplish
this task.

Thanks.

--
Tony Kava
Network Administrator
Pottawattamie County, Iowa