What I would like to do involves a small bit of hardware. 1) a phone headset, 2) a PCI-modem, and 3) a phone wire. What I would like to do is read audio from the modem, and then digitize it for processing. I'm sure the best way to do this is with Linux, but if it can be done in Windows as well that would be awesome. A second extension of this, is that I would like to be able to translate digital audio to analog audio and send that to the modem so it can be heard from the headset.
Any advice would be greatly appreciated. ( Also, if anybody has a general "pointer" to what I should investigate to replicate the audio stream to a TCP server so it can be accessed over LAN, that would be even cooler. I know how to handle TCP well enough, but I haven't a clue about audio encoding / decoding ).
If anybody's curious, I'm wanting to create a home-wide audio-stream with ears and mouths. Since the phone cables can do that with normal headsets, I thought "why not".
Not just any modem will do. You need a "voice modem", which includes audio capability as well as general modem functionality. These devices usually expose themselves as a regular sound card on the system, once the drivers are installed. From there, you can use any mechanism you want to read/write from those audio streams.
Be warned though that your plan of a whole-house speakerphone isn't simple at all. There are significant feedback issues when using regular POTS lines. There are entire companies that work to solve this problem. The best of them use microphone arrays that are steerable in software. You would be better off using one of these off-the-shelf systems.