Am I correct thinking that a AT&T and T-Mobile phone can use LTE in Canada if I put a Canadian Sim card in my phone and Sprint and Verizon will be 3G?
that is correct.
Current Gen Unlocked iPhone 5(A1428) sold by Apple Store aka AT&T(A1428) will get 3G/4G/LTE on Rogers, Telus, Fido, Bell, Virgin and Koodo Mobile.
Tweaked iPhone 5 for T-Mobile will get A1428:
- 3G/4G Service on Rogers, Fido, Telus, Koodo, Bell, Virgin, Wind Mobile and Mobilicity as well as other regional carriers, Basically the new iPhone is going to be a TRUE WORLD iPhone.
- LTE on Rogers, Fido, Telus, Bell, Koodo Virgin and possibly Wind Mobile & Mobilicity depending on what bands they launch it on in the near future, I know Wind has launched a "4G" network and that should be supported for sure.
Sprint & Verizon iPhone's will only provide 3G service as well as any customer that brings the International A1429 model to North America will get 3G/4G Service...No LTE (mainly because Verizon & Sprint will never allow any iPhones not sold by them on their network) that too on AT&T, T-Mobile (in 1900MHz areas only), Rogers, Fido, Telus, Bell, Koodo, Virgin Canada...NO Compatibility for Wind Mobile or Mobilicity.