Not at all. The phones that have the 2100MHz band, use it in conjunction with 1900 for uplink and downlink (I can't remember which is which)
The same occurs with any two way GSM band,
http://en.wikipedia.org/wiki/GSM-1800#GSM_frequency_bands
Edit: ah, mch explains AWS's 2 frequency bands..
The same occurs with any two way GSM band,
http://en.wikipedia.org/wiki/GSM-1800#GSM_frequency_bands
Edit: ah, mch explains AWS's 2 frequency bands..