I'm hoping someone can help me figure out how to wire up a speakerphone to a
headset jack.

I bought a USRobotics ConferenceLink Speakerphone from Heartland America for
30 bucks. Originally 400 or so. That's the good news. What they didn't
tell me was that it is designed to work with PBX's (obsolete ones at that)
and it _won't_ work with analog POTS lines. I'm a techie, so rather than
send it back like any rational person, I am determined to make it work.

It comes with the connector for the PBX (worthless), but because it's
USRobotics, it also comes with a connector to two mini-jacks that are
line-in and line-out to a computer sound card. I tried it with my
speakerphone-enabled modem card and it works. The qualilty is not good,
however, because of interference inside my home-made computer box (my
guess).

Then I got this bright idea. I have a great Sony handset that has a headset
jack. In the end what I want is the speakerphone to connect into the
headset jack of the Sony handset. To make that work, I need to bridge
between the 4 wire (line-in and line-out) jacks to a headset jack.
RadioSnack doesn't have anything built for it (I've tried). I'm willing to
cut wires and have the appropriate jacks to do it, but I'm confused about
what to attach to what. There are two wires each going to the line-in and
line-out jacks from the USRobotics ConferenceLink. It looks like there are
two (maybe three?) going to the headset. Can someone tell me how to connect
this up?

Thanks in advance for your help!

Matthew Lonergan