If it's a rural site 2100MHz won't be used. The only time 2100MHz is really used is for urban infill since it has a very limited coverage area. You'll find that site will only be 850MHz dual carrier.

Dual carrier (Wikipedia) doesn't bond 2100MHz and 850MHz, it bonds 2 of the same channel on a supported device to give you (up to) 42mbit down, 5mbit up.