HP82915 Modem

I recently won an HP82915 Modem on E-bay (my first, and so far, only purchase there). I was suprised to get it for the opening bid, I though I'd have at least one other HP collector to contend with. It is, you see, the internal modem for the HP Integral. Anyway, it's a single PCB that fits into one of the Integral's expansion slots. Cotnains about 20 ICs, most of which I recognise. One odd thing is that the serial chip used is an 8250, a somewhat odd choice for a 68000-based machine. Does anyone here know anything about using it? The Integral manuals I have mention it exists, say it installs like any other board, and that you need a normal 'modular phone cable' to link it to the phone line. Nothing I'd not worked out by myself. Incidentally, I have no intention of linking it to a public phone line, I just want to connect it to another modem. I suspect it'll work withont any DC voltage on the line, if not, that's easy to fix. Did anyone, though, have a cheap/homebrew device to link 2 modems back-to-back, doing things properly with dial and ring tones, etc? -tony