sorry to resurrect this old thread, but I just found that HTC Service menu allows you to select GSM/UMTS band
*#*#4636#*#*
This code can be used to get:
Phone information
Battery information
Battery history
Usage statistics
and under phone information, there is a setting for network selection, allowing toggle between GSM only, CDMA, etc.. This one gives more options than going to mobile network setting through the menu.
Once you enter the code, press the menu button (next to home) you will get the following options:
Select Band Radio | View Sim Address book
-- ------
View Fixed Dialing |View Service Dialing Numers
Numbers
-- ----
Once you chose Select Band Radio, it will ask you for GSM/UMTS band, ranging for Automatic, EURO band, USA Band, Japan, AUS Band, AUS2 band.
I'm wondering if any of these will work on ATT 3G..?