Ok, this is a simple one.
Dont do what you are doing.

Go to  http://www.mitelsemi.com/
and look up the MT8843

It does everything for you.
The unit can either send you the data Via ascyn or sync.

Muuuuch easier than trying to get a modem chip to do it.


>So, I assume that I must use the synchronous mode of data transmission,
>and as I understand it, this means getting my sender (the PIC) and the
>receiver (the modem) handshaking at the same rate, and I don't know how