Friend
what are the digits that will be sent to you by the provider
here is a sample config
card type e1 1 1 (required for 2Gen cards)
controller E1 1/0
framing NO-CRC4 (will depend on ur service provider)
pri-group timeslots 1-31
isdn switch-type primary-net5
dial-peer voice 1 pots
destination-pattern 9.T
incoming called-number .
direct-inward-dial
port 1/0:15
!
dial-peer voice 2 voip
destination-pattern 800 (will depend on the digits sent)
session target ipv4:
Also you will have to use a translation pattern to translate the digits that are sent by ISP to your extension range
HTH
Narayan