How to make extension use Zap/2 if Zap/1 is being used?

I didn’t see this covered in the O’Reilly book and I don’t see how to implement it in the extensions.conf file. (I searched multiple zap channels and multiple lines but I didn’t find anything)

I think that’s what zap groups are for. e.g. put zap/1 and zap/2 into, say, group 0, and specify the group in the trunk?

Ok. I found out how to do it after dswartz said it was called groups.

Edit your zapata.conf to include group=1 (or whatever number you want) before the line “channel => 1,2,3,4”. That assigns all those channels to group #1.

Then, instead of
you have

and Asterisk will dial out on the first available line in that group.