[Asterisk-Users] Delaying answer of incoming calls

[Justin Ridge]

Hi all,

I'd like Asterisk to answer an incoming SIP call and bridge with a POTS 
line.  However, I do NOT want Asterisk to answer the SIP call unless the 
called POTS number answers (otherwise SIP caller is charged).

The wiki says this is the default behaviour, and so does this message
http://lists.digium.com/pipermail/asterisk-users/2004-April/041881.html

But it's not working as expected.  The SIP call is answered immediately 
before the POTS line even starts ringing.

The dial plan is simple:
[from-sip]
exten => s,1,Dial(Zap/1/*829xxxxxxxxx,20)

I don't have "Answer" in the dial plan.  I don't think I changed any 
settings that would cause this non-default behaviour, but can you help me 
find why this is happening?

Thanks
JR