aralebd

That's the whole point, the modem does not have a physical I/O, only the sound card has one.
Otherwise it would have been speakerphone supported - but as I said earlier it's not speakerphone supported (By the way all speakerphone supported modems are full duplex by definition).
I just go further and say that since the modem can record wav files (Or even mp3) I'm sure that it's possible to imitate the speakerphone facility by software using temerary wav files buffering as an audio stream for the sound card in a similar manner as one hears radio streams from the internet. So I thought may be one of you guys know about a software that does it.
By the way duplexing here might seem a bit hard because of the question wheter we can buffer both ways simultaneously or say fast enough. But I think that my Pentium IV with 2.8 GB clock or say today’s computers which are even better, should be able to handle it quite easily.
another thing: I'm not iterested in Netmeetings or any kind of messengers (I already have that) because the whole point is to connect the PC to the regular phone line to answer ordinary phone calls using my computer without the need for my telephone apparatus on my desk.
Finally I want to add - If no such software exists it's a damn good idea to write one, But I just can’t believe that I’m the first one who thought about it.