As usual, nothing's simple:
http://en.wikipedia....ier_Frequency_Use
Frequency bands (MHz)
Vendor: Voice 3G 4G
AT&T 850 (Band 5)/ 1900(Band 2) 850 / 1900 700 (Band 17)
Metro PCS 1900 / AWS 1900 / AWS AWS
Sprint 1900 1900 2500 / 1900 G-Block
T-Mobile 1900 AWS/(1900(limited)) AWS/(1900(limited))
Verizon 850 / 1900 850 / 1900 700
http://en.wikipedia....n#Frequency_bands
The LTE standard can be used with many different frequency bands. In North America, 700/ 800 and 1700/ 1900 MHz are planned to be used; 800, 1800, 2600 MHz in Europe; 1800 and 2600 MHz in Asia; and 1800 MHz in Australia.[24][25][26][27][28][29] As a result, phones from one country may not work in other countries. Users will need a multi-band capable phone for roaming internationally.
Are there such multi-band capable phones? http://www.mobileeur...upport-on-the-way
And it seems that multi-band LTE devices are also becoming more common: five so far in 2012. The last three devices certified have been tri-band LTE incorporating the 2100, 2600 and 800 MHz bands which allows the devices to be targeted at both Europe and Japan. There have been no LTE1800 devices submitted yet. All the LTE devices certified this year have also incorporated at least dual-band 3G in the 2100 and 900 Mhz bands. (Quad band GSM/EDGE is also virtually ubiquitous).
Bah.
As usual, one has to wed oneself to a particular carrier for the life of the phone. Though in principle one could switch between AT&T and Verizon, it won't help in Europe or elsewhere.
Cheers,
Scott.