Yep, I know you need called ID and Waiting (Not neccesarily waiting but
definitly caller ID). They have all that.
You need THREE things from your phone company: Caller ID, Call Waiting,
and Call Waiting Caller ID.
Then you need a modem that supports reading the caller-id message and
the v.92 "modem on-hold" protocol, an ISP that ALSO supports v.92 (so
you can put your session on hold and answer the phone), and some m-o-h
software.
The m-o-h software will sit and watch the modem. When it gets the call
waiting signal it will pop-up, tell you a call is coming through, and
give you the option to put the session on hold and answer the phone.
Note, I found that this ONLY works with phone physically attached to
the modem. YMMV, but that's how it was with mine.
The m-o-h software may or may not read the caller-id signal and display
it. You should ask.
That's a LOT of ducks to get in a row. Good luck
Eric