Try adding "M1" to your initialization command.

>Dear Sir/Madam
>
>I have developed a programmed which dials through modem. But there is one problem when after dialing the oponenet picks up the phone his voice is also heard in the modem speaker. I am using samsungs External Modem. There is some initilization command. AT commands. Please advise or suggest some site where i can get the solution.
>
>Rahul