>I have developed an Address Book and if I want to dial a number please give me the code how to write and whre to write. Take as if I am a beingner in communication part.

Hi, Rahul.

I'm not an expert in that field, but seeing that you don't have another answer as yet, I want to point you to some of the controls provided with Visual Studio.

There is a Microsoft Communication Control that should give you access to the installed modems.

Just take a look at that. Hope you can make it work.