Re: [Sheflug] Mobile Linux

[Alex Hudson <nospam [at] york.ac.uk>]

On Tue, 20 Jun 2000, José Luis Gómez Dans wrote:

> > I'm trying to find out how to link my mobile phone up to a laptop. 
> > All of the present mobile phones use infra red to transmit data from
> > the laptop to the internet.  My laptop doesn't have an infra red link
> > on it and I'm not going to buy another one.
> 
> 	This isn't true. Most mobile phones I know of (all of them, in
> fact!) do not have an IR port.

Sort of. All new phones have IR. At least, all those new ones which aren't
toys.

> Usually, you can get a cable you plug in
> the cellfone and on your laptop's serial port. At least, it used to be
> like that. I don't know what particular phone you have, but if you have
> a Nokia one, you might be interested in visiting the gnokii webpage
> (look in Freshmeat). In general, what your phone does is to act as a 9k6
> modem between the laptop and th PSTN.

Gnokii is currently not in a working state, although if you want to read
addresses from a phone it's okay. The Data transmission is extremely
flaky, though. http://www.gnokii.org/, I believe. Compiles okay for me,
but there's a lot of basic errors, and I'm not convinced of the code
quality. They claim to have written a daemon, gnokiid, but it doesn't even
separate from the console - I don't expect the quality to improve
amazingly quickly, although it's much better than it was.

> 	I'm not sure that anyone has written any software to actually
> fiddle around with the EPROM the mobile phone has (so you can download
> the phone directory and stuff like that).

Both the RAM on the phone (most phones don't have E2PROM for anything
other than system settings), and the SIM areas are accessible from gnokii,
or example. Probably precious few other phones though.

> 	But definitely, no IR port needed. have a look at gsm-cables.com
> (or similar, sorry!).

Whether you use a cable or IR, the upshot is the same: the phone does not
present a Hayes interface to the computer; you need software. If you look
at the circuit diagrams for the cables, there's nothing to them: simple
MAX232 charge-pump design, simple voltage regulation (3.6V+ tends to smoke
mobiles), so it's a basic RS232 interface. But the modem on the phone is a
little more akin to a Winmodem, in that it needs a software interface to
present the Hayes interface. GSM Modems are sufficiently different to make
this really difficult: the packets you pass to a phone are very strange.

Speed is 9k600, as mentioned, which is ~1Kbs-1. Orange are upgrading later
this year / early next to 14k4, which is a little bit faster. GSM
theoretically scales to a couple of megs a second per cell, which over
1800(PCM) should mean faster than 14k4. Each 1800 cell is a few miles
square (urban network), so 2Mbs-1/1.5Ks-1 gives approx. 1'500 max users.
Maybe a problem in London, but it should be quicker. Bring on g3 ;)

(BTW - if you want to be 14k4 ready, the 7110 is the only phone that does
it, to the best of my knowledge - even the 8210 doesn't. Ignore that wap
business, though, it's a crock ;)

Cheers,

Alex.


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