[Asterisk-Users] Ringing Delay

[chan (Alpha Trilogies Networls)]

Hi,
Can some one advice me that how can I make the FXO channels port answer an
incoming calls, means when I call from Lan line to Asterisk TDM400, my phone
get ring immediately. When POT FXO port is ringing, Asterisk seems like
studying the incoming ringing pattern even it did answer the call.
I did not activate the usedestingtive, but why it seems delaying an incoming
calls?
Normal PBX, say will only delay 1 cycle as max in analog line, but Asterisk
is about 2 sec...???