>My problem is that once the link is connected, it tends to stop talking
>after a few minutes. Anywhere from 30 seconds to several minutes after
>the link is established, it simply stops talking. The modems are still

Try running pppd in debug mode (which you would specify in the appropriate
config file, see pppd(1) for details).

pppd will send its debug information to syslogd, which will put it into
the file you specify in /etc/syslog.conf.  I believe the messages are logged
with type daemon.debug, but I could be wrong.  See the manpage for pppd.

Anyway, once you've got a file filling with pppd messages, watch it with
       
"tail -f /var/log/ppp_debug" or whatever file you told syslog to use.  Then
dial up your ISP, start a ping (say to your default gateway) and watch the
messages in the log.  Be especially interested in the messages you see just
as your pings start to fail.

If you're still stumped, paste a portion of the debug output which you believe
is relevant into this list.. I'm sure someone will know what's going on.

Jonathan Fuerth