Proposal v2: identifying modems and mobile broadband cards

Faidon Liambotis paravoid at
Mon Feb 11 11:05:05 PST 2008

Dan Williams wrote:
> - An interface with the 'modem' capability may also acquire the property
> 'modem.at_command_sets', which is a string array of supported command
> sets, denoted by their abbreviated standards name. If the property is
> present, it is assumed the modem supports rudimentary Hayes-compatible
> AT commands.  The key may contain _one or more_ of the following values:
>    a) IS-707-A  (for CDMA supporting cards)
>    b) GSM-07-07  (for GSM supporting cards)
>    c) GSM-07-05  (for GSM supporting cards)
There are some GSM/UMTS/HSDPA cards out there that are based on some 
Qualcomm chipset (namely, the Novatel ones, including the ones found on 
recent Dell laptops) that support the GSM command set on ttyUSB0 but a 
completely different binary protocol on the management port, ttyUSB1.

This binary protocol is called BREW[1]. On the Novatel card that I own, 
it is possible to pass-through the standard GSM AT command set via BREW 
and I've made some success towards this point.

In the event that I manage to complete the reverse engineering (I'm not 
very far from it), it'd be nice if HAL would transparently support 
talking to the management port. Not sure how, but it seems like a good 
time to include this on your plan.

BREW is apparently used on some CDMA cards but I have no idea if the 
same AT command passthrough works there.
May be this should be yet another key for those CDMA cards, not sure if 
(a) includes it.

Note that there is already a free software implementation for a part of 
BREW, called BitPim[2]. This software is for CDMA phone management 
(phonebook, SMS etc.). Unfortunately, there are no indications that they 
are even aware of the AT passthrough feature.



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