With the most recent beta for iOS 6.1 Apple has enabled 4G LTE in the iPhone 5 for more carriers including Zain Saudi and UAE’s Du.
After installing iOS 6.1 beta 2 Enable LTE will appear in Settings General Cellular if you’re using a SIM card with a supported 4G LTE network (Zain uses 1800Mhz).
I managed to test Zain Speed 4G on my UK iPhone 5 with no issues other than coverage.
Zain’s 4G LTE band is supported on most global iPhone 5 units (model number A1429) as well as iPad 4 model A1460 and iPad mini model A1455.
STC and Mobily’s 4G LTE currently do not support iPhone 5 LTE. We have to wait until these companies change their network to support the iPhone and other devices.
You can find the author of this post on twitter: @khaled.