Using GPRS/CSD Modem of Siemens S45 on the O2 Ireland Network

This page provides information on use of the Siemens S45 mobile phone with Linux. While all the information listed here has only been tested on my own system, it's pretty generic and most information should, I imagine, be useful under other OSes (*BSD, OS X, PalmOS...) and (to some degree) networks/phones. The system I've used it on is as follows:

Toshiba Satellite Pro 400 CDT (75MHz P1 cpu, 40MB RAM) running Debian GNU/Linux 3.0R1 (Woody), stock 2.4.18-i586tsc kernel. pppd Version 2.4.1. Siemens S45 with provided Serial Port Cable. O2 Ireland network, monthly bill service, with minimal GPRS service.

At present there's info on the following topics: