remote serial console on Ultra 10

[Marcin Sochacki <wanted@gnu.univ.gda.pl>]

Hello,

I have the following setup:
- Sun UltraSparc 10 machine,
- Happy Meal fast-ethernet interface,
- Creator 3D card with VGA monitor,
- Debian Potato.

The server is connected in some remote place, so I can easily connect
there using SSH when everything runs fine.
But the problem arises when something goes wrong and I need access to
the console.

I'm thinking about connecting an external modem and dialing there
in case of failure.

How do I configure the following:
1) remote access to OpenBoot console,
2) remote access to SILO prompt and Linux shell?

The modem is Multitech MT2834BLK, which is said to be very good for ISP
applications.

Marcin