Re: Mobile broadband connects to wrong USB device

[Dan Williams <dcbw redhat com>]

On Tue, 2009-01-06 at 16:03 +0000, Rick Jones wrote:
> --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.

With this, my Sierra 860 doesn't respond and times out.  Were you ever
able to find out from the MobileStream guys why this might be required?
It might also be something that NetworkManager isn't doing when setting
up the serial port.  Does USBModem need specific serial port settings?
 
> 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.

With this also, my Sierra 860 doesn't respond and times out.

> 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.

What's the init string you currently use?  Long ago you mentioned:

AT&F\rATV1 X4 &C1 +CREG=0

Is that still correct?  Or can you move the AT&F after the \r?

> 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.

The Sierra 860 also doesn't like AT&F *at all*.  Whee!  If we can put
together an init string that works for now, we can add it to the bottom
of the list.

Dan