Re: Mobile broadband connects to wrong USB device

--On Tuesday, January 06, 2009 15:00:50 +0100 Patryk Zawadzki <patrys pld-linux org> wrote:

¦ Allowing one to edit the init string is a security threat similar to
¦ allowing users to provide custom firmware.

OK, i can see there's an issue there.

¦ Other than that there seem to be only two differences between devices
¦ reported so far. One is the initial echo state which is insignificant,
¦ the second one is whether the device supports ATZ or requires AT&F +
¦ defaults.

Not true. I've reported here on more than one occasion the problems with my modem.

a) it requires an initial <CR> otherwise it fails to see a clean AT command and doesn't respond - resulting in an init. timeout.

b) its initial CREG state is 1, meaning that NM gets incorrect responses to its CREG queries later in the conversation. It requires +CREG=0 in the init string.

By hacking these fixes into the init string it works fine. It's a soft modem running in a Palm Treo handheld: USBModem by MobileStream. At least one other poster on this list is using (or trying to) the same software.

Regarding ATZ v. AT&F, I believe the latter should always be supported, as it is a full reset. ATZ restores to settings saved using AT&W, but if that's never been used it's the same as AT&F. If AT&W is not supported, then ATZ may not be either; and if you don't use AT&W to save settings (does NM?) then there is no reason to use ATZ.

Cheers, Rick

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