For the phone to make and receive phone calls, it must be registered with one of the available networks. Your phone can handle combined GSM 900/1800, GSM 1900 network, and Quad band (GSM 850/900/1800/1900). The country where your phone was purchased determines the default band that it uses. When you travel abroad, you must remember to change to an appropriate band.
1. From theStart menu, tap Settings → Personal tab →Phone.
2. In theMore tab, tap Band Selection → Get settings...
3. Select an appropriate band in theFrequency Band field.
4. Tap .
I have a Blackjack II and I would like to get the i-780 unlocked but I want to make sure it will work in the US on the AT&T network. I checked the band selections on my Blackjack II using bandsel.exe within windows. The options are
2. GSM 850
3. GSM 1900
Can someone with an i780 check these settings to see if they are available?