GSM Mobile Phones and Linux

Capability

GSM mobile phones can in principle make ISDN connections and can thus subserve internet connections via conventional Information Service Providers (ISP) or send and receive faxes.

Hardware requirements

To use a phone together with a computer (generally a laptop) a connecting cable is usually needed, sometimes together with a PCMCIA card that provides "modem"-like capabilities. In some cases phones are equipped with built-in or accessory infrared interfaces meeting the IrDA standard, in which a laptop with an IrDA port can communicate with the phone within IR beam range. These devices are not really modems, as the phone is not doing audio modulation/demodulation, but they are generally called modems nonetheless.

In addition there are dedicated data/fax devices that do not provide voice or manual dialing capabilities (see for example the Nokia Cardphone).

The hardware link between computer and GSM phone may also allow sending messages from the computer to other GSM phones using the Short Message Service (SMS).

Software requirements

GSM modems generally come with software packages, mostly designed for MS-Windows, and information on the Web usually states MS-Windows compatibility. Finding out whether a phone/modem will be usable with Linux is not easy. Retailers will usually state categorically that no phone/modem can be used with Linux, suppliers will usually say the same, or if pushed will admit they do not actually know. Manufacturers in my experience will not answer the question.

I was pretty desperate to find a modem, and in the end took a gamble based on some very scanty information and bought a PCMCIA modem for an Ericsson GSM phone I already had. It worked on first attempt using ordinary AT commands using a serial device, just like an ordinary PCMCIA modem (for which you need to compile PCMCIA kernel modules and enable PCMCIA card recognition). In other words, any Linux software designed to work with ordinary land-line modems will work with such a phone (see the list below). This includes fax software like efax. In the meantime I gained access to an IR modem for another Ericsson model and discovered that the Ericsson IrDA modems also accept ordinary AT commands. Together with IrDA for Linux these modems can also be used with any Linux modem support software. (Note: as of Linux-2.2.12 with the IrDA patches applied, this system works perfectly.) The Linux Infrared HOWTO pages give advice on how to do this.

If the GSM-modem also supports modern GSM/SMS specific AT commands, it may also be able to pass short messages to the modem for injection into the SMS system. (See also restrictions below and the note on SMS at the end of this document. start with SMS Tools.

Ericsson models known to work

The following have been used by me or reported by others to operate:

Phone	Modem	by
GH388	DC23 (PCMCIA card + cable)	Dave Davey
GH688	DC23v (PCMCIA card + cable) or DI27 IrDA accessory modem	Dave Davey
GH788	DC23v (PCMCIA card + cable) or DI27 IrDA accessory modem	Dave Davey
GH888	IrDA built-in modem or RS232 Cable (but still requires IrDA layer!)
I888	IrDA built-in modem	Dave Davey
GS18	Built in RS232 modem	Brian Lawless
T18s	DI27 IrDA accessory modem	Simon Boggis
T28s	DI28 IrDA accessory modem	Simon Boggis
T39m	Serial cable - GPRS & CSD	Mikko Rapeli Settings available here
T65	Serial cable GPRS mode	Kalle Raiskila
T68	Serial cable & IrDA GPRS mode	Mikko Rapeli Settings available here
R320	Built in IrDA	Jan Marius Evang Marc Gloor
R380	Built in IrDA	Alberto de Vega Luna
R520m	Serial cable - GPRS & CSD	Mikko Rapeli Settings available here
T300 GPRS	IrDA (see How-to)	Todor Tanevski

Bosch models reported to work