Verizon Wireless has confirmed that its LTE phones will not “be compatible on other LTE networks in the U.S” due to frequency differences, according to a PCMag report. The article notes that although the new 4G LTE system being implemented by Verizon, MetroPCS and AT&T uses a SIM card system similar to GSM, carriers such as Verizon may be building phones to run only on their own wireless frequencies, preventing their devices from being used on competing networks, even for roaming where Verizon-specific LTE coverage may be unavailable.
Although both Verizon and AT&T use the 700MHz LTE band, their networks use different frequencies within that spectrum with very little overlap. Other U.S.
carriers use 1700MHz and 1500MHz frequencies, while even more LTE bands are available to international carriers, suggesting that it may also be challenging to roam internationally with LTE devices. It is unclear at this point what plans other carriers such as AT&T have with regard to the frequencies used by their LTE phones, and whether Apple will be able to offer universal LTE world phones that avoid the need for multiple versions.