isdn in Luxembourg

hello I have some problems connecting to the internet via linux SuSE 6.0 using a Fritz card what should I use for MSN when configuring the parameters with YAST? I read that in Austria they have a similar problem one single phone number without area code and area prefix. I tried MSN with my own number, with the number preceeded with 0 and with 0 alone, but nothing works (error message "incoming call without CPN"). And in Switzerland it is different to. Thanks for your help and understanding. Pierre