Incoming call problem in PRi E1 line

We are having a call centre and now planning to replace with Asterisk. We got a Digium PRI card 1TE122PF and have done all configurations for interfacing the card with the PRI E1 line we are having. As if now i need just the call from outside to land on asterisk. But its not hapenning from the line. We have configured the /etc/asterisk/chan_dahdi.conf, /etc/asterisk/extensions.conf and /etc/dahdi/system.conf.
As we are new to Asterisk Plz check these and give some sugessions. Any kind of sugessions are welcome.

Thanks in advance.

Can U please copy paste your configuration details for Chan_Dahdi.conf, extensions.conf ?