>it looks like a phone handset connector, but i'm somewhat willing to
>bet that it's not electrically compatible with one.  I dunno for sure,
>though.

Actually, I am pretty sure that it is compatible with a handset.  The
audio chip used in the 3000 family is designed for use in ISDN phones
(and in fact is also in the ISDN phone on my desk :-) ).  The chip
can drive a handset directly.  Also, I have used the audio ports
on some of the VAXstations by plugging them into handsets.  So it
seems reasonable that the same thing could be done on this guy.

>I seem to recall 3000-family machines being shipped with headsets,
>i.e. speaker on a headset, and either a separate mike or a mike on the
>headset itself.

I think I might pick up a headset from supply, then :-)

>Which 3000 models have mini phono jacks?  the just 3000/300 faimly?
>or other [4-9]00 models?

According to the System Programmer's Manual, the 500, 800, and 900.
The manual _also_ explicitly says that the jack on the 300 is compatible
with a handset.  For the others, it says "the audio lines come out of
a connector on the rear of the enclosure".  I don't know what that means,
though :-)

--Ken