[Asterisk-Users] Excessive Asterisk delay to answer on ZAP inbound call

[Giorgio Incantalupo]

Hi,
I have an asterisk 1.2.1 on a Debian Sarge distro with *three* TDM400P 
(12 fxo ports). I noticed Asterisk is slow to answer inbound calls so I 
connected an analog phone in parallel to make a test:

                  __________Asterisk fxo
---- line -----|
                 -----------------Analog phone

The analog phone rings immediately when calling, while asterisk shows 
the message "Starting simple switch on zap..."  after the first ring and 
executes the old extension script after the second ring (for example a 
NoOp instruction).

Why does Asterisk wait for these two rings? What is it doing meanwhile? 
Is it possible to shorten this interval to have an immediate response?

TIA

Giorgio Incantalupo