> I think that you are getting bitten by the fact that, on Unix type
> systems, open on a tty blocks if the carrier detect line isn't asserted.
> Which makes it kind of difficult to send Hayes style commands to a
> modem which isn't already on line ...
> 
> If you really want to mess with stuff yourself then take a look at the
> "softcar" parameter to /etc/ttys ("man ttys").

Thanks to everyone who replied to this one - I think the above was the
problem.  I actually managed to get things to work by a combination of
using stty to fiddle with clocal and (I think) cread, and sending the
output to another ttyp.  Anyway, things are working now and I can go and
set-up ppp, safe in the knowledge that the NetBSD <-> modem bit works!

Thanks again,
David.