Fritz problem


#1

isdn line
Fritz card
Asterisk
x-Lite soft phone

when i call my home phone i got signal on x-lite and conversation goes on, but when i call my cellular from x-lite i get cellular ringing but there 's no voice. I turned off cellular , call again from x-lite, got busy signal, and got information from my telecom that i have been called.
WHAT might be a problem?