ISDN problem with MSN

Welcome,
I have a range of phones numbers connected with my PRI Isdn.
My card is 4xE1 using tor2 module. How can I associate this numbers
with each channel. When I am calling this numbers I hear something
like busy signal and see nothing in Asterisk.
However I can call from this channels outside.
I will be very glad if someone could send me an answer.

Regards
Przemek