Win32 - Cannot make calls to landlines


I hope my english is good enough for describing my problem :wink:

Iā€™ve got a server running on Windows XP and AsteriskWin32 installed and an ISDN-Card ā€œEicon Diva Serverā€.
When I call a mobile phone the connection works, that means, that I can speak and the other can hear me.
When i call a landline number the phone rings for a second and over my softphone i can hear a lady talking to me ā€œcongratulations, you have successfully installed and started asteriskā€¦ā€ - and there is an ISDN-Channel used, like the call would be established.

I hope someone can help me unless my english is terrible :smile: