1)  If you're asking about Multi-Link PPP, I don't know if NetBSD
    supports it.  I haven't seen anything in the docs to indicate that
    it does.

2)  I've seen similar problems, where my modem connects and then
    disconnects shortly thereafter, when my modem just wasn't talking
    correctly with the modem on the other end.  What we always tell
    our customers is, "upgrade your modem driver."  It sounds silly in
    this case, but it might make sense -- apparently, modem drivers
    often include something called "modem code," which is some sort of
    low-level code for talking V.90 (or whatever).  It's stored in
    NVRAM in the modem, so putting the modem in a windows machine,
    downloading and installing a new driver from the manufacturer, and
    putting the modem back in your NetBSD computer might work.

Of course, it could be something completely unrelated.

Chris

-- 
-----------------------------------------------------cjones@math.montana.edu
Chris Jones                                          cjones@honors.montana.edu
           Mad scientist at large                    cjones@nervana.montana.edu
"Is this going to be a stand-up programming session, sir, or another bug hunt?"