GSM roaming question

Harald Welte laforge at
Wed Oct 7 22:04:11 CEST 2009

On Wed, Sep 30, 2009 at 12:48:14AM +0100, Al Johnson wrote:

> Automatic mode means the gsm firmware is in control of which network it 
> registers to. This should be the home network if available, or any other 
> allowed network if not. There is an AT command to list the order of preference 
> for picking other networks, but I don't remember what it is, or whether it is 
> provided by the SIM. It's not something you should normally need to touch 
> though.

it's the preferred operator list, stored on the SIM, and typically you can even
edit that file on the sim card (i.e. the filesystem permissions of the SIM's
internal FS permit modifications).  Motorola EZX phones or very old siemens
S2/S3/S6/S10 have the feature to add/remove entries to the preferred operator

I agree, in normal operation you should never have to care about these.

- Harald Welte <laforge at> 
"Privacy in residential applications is a desirable marketing option."
                                                  (ETSI EN 300 175-7 Ch. A6)

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