There are only two GSM networks in the USA (the rest is CDMA):Even with a few working bands? That's dumb. I wish only ones America would go what the rest of the world does and not always make it so it won't work. Always those stupid extras. Annoying. Just go by the standard. Just ones. Roll eyes. Lol
- AT&T: LTE band 4 (1700/2100 MHz) and band 17 (700 MHz)
- T-Mobile: LTE band 4 (1700/2100 MHz)
The C6603 only supports LTE bands 1 (2100 MHz), 3 (1800 MHz), 5 (850 MHz), 7 (2600 MHz), 8 (900 MHz) and 20 (800 MHz), so none of the North American bands.
The problem with LTE is that they had to find free frequency space in many different parts of the world (with many different frequencies already in use). The result is a huge list of different bands worldwide: https://en.wikipedia.org/wiki/E-UTRA#Frequency_bands_and_channel_bandwidths