GSM frequency bands in the USA

Michael Spacefalcon msokolov at ivan.Harhan.ORG
Wed Feb 26 05:44:32 CET 2014

Nick <openmoko-community at> wrote:

> It's interesting to hear that 850MHz is a quite recent addition, 

Just keep in mind that my idea of recent is "within the last 10 y",
at least in this case; most other people's definition of this word
probably means a shorter time span. :-(

All I know is that back in 2003 phones sold in USA with carrier
branding were typically 1900 MHz only; I don't know when 850 MHz
support began to be considered as a "requirement".

Of course all those proprietary 3G+ smartphones (Apple/Samsung/GTA04/etc)
which we are all surrounded with typically act as quadband when they
go into 2G compatibility mode, but because they are proprietary black
boxes, only Cthulhu knows which band they are using and what is the
total set of signals they "hear" across their supported bands.  So I
still don't know for certain to this day what GSM services, if any,
exist in the 850 MHz band in my area.

> thanks, that makes me feel even more confident about my GTA02's 
> chances.

I wrote earlier that I only use T-Mobile USA.  That status still holds,
but earlier today I did an experiment: I walked into an AT&T retail
store with one of my Pirellis (900/1800/1900 MHz only, no 850, just
like EU-Freerunner), got a test SIM from the guy in the store (he
pulled it out of one of their demo phones), and inserted that "random"
AT&T SIM into the Pirelli.  After displaying "Searching..." for a
little while, it worked!  The display read "Cingular" - so now we know
that the operator name decoding table in Pirelli's fw is the same as
the one we've got in our sources. :)  Going into the "Engineering mode"
menu confirmed that the actual network in this case (AT&T in Southern
CA) is 310410.  A test voice call worked fine too.

So now we know that *both* GSM networks in USA (or at least in SoCal)
work OK with FreeCalypso GSM phones - although I would still recommend
T-Mobile to non-adventurous users, simply because it's been tested a
lot more extensively, including fun things like CSD.


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