[Asterisk-Users] extensions

[tns]

I have a question regarding extensions.  I understand what is going on in
the extension described below.  But my question is as follows:

I have a TDM400P 4-Port FXS card.  What would my Zaptel Interfaces be
(Zap/1-1 for the first port on the card)?

exten => 7100,1,Dial,Zap/1|24

And then how is the trunks defined as Zaptel interfaces.. In the sample
extension file it has Trunk set to Zap/g2.. Where does this come from?

Thank you,

Geoff Clark