I am interested in creating an arduino project that has the function of a plantronics headset amp.. Basically you could plug in a headset, plug it into the phone and it would have a volume control, and mute and "mute other party" button. Plus maybe a few extra things.. whatever I though of... maybe a 1/8th inch in so I could listen to my iPod between calls. I think this is entirely within the ability of the board.
Am I mistaken?
Sure...to get a head start, see if you can find a Radio Shack Headset/Handset Switch. They stopped making them last year. Thankfully, I managed to buy two. It was a great device...you put in a couple batteries, plug it in between your desktop phone handset and the phone body, then plug in any 2.5mm phone headset. And it only cost five dollars. Pity they stopped making it, that was the only useful product in the store. Of course you can buy a system with the same function and Plantronics branding for upwards of 99 dollars.
Anyway, that would be a good way to get access to the telephone audio. Next, the device could route the signals to 3.5mm jacks so you can use a regular PC headset and boom mic for the telephone. Pipe in stereo music, maybe use an analog mux to switch and mute sources. I want to build one that senses the phone ringing by watching the activity LED, and automatically mutes music until the call is over. And lights a big "ON PHONE" sign over my desk.
Oh! Those are awesome suggestions! Thank you! My reason for wanting to try this is because plantronics amps and headsets are ridiculously expensive. This would definitely cut down on costs, At work when I get a call a DTMF beep gets piped to the headset, I could probably set it so that it automatically unmutes me when it hears that tone.. Thanks. I've got a lot of research ahead of me. =)
I quite like the idea of making an Arduino generate DTMF (Dual Tone Multi-Frequency) signals, and hence dialling numbers. Some years ago, you could buy small boxes with a keypad and speaker that would do just that, for use with pulse-dialling phones on lines that would accept DTMF.
It might also be fun to generate Quindar tones, as used by NASA in the Sixties to control the radio gear that they used on the Apollo missions: