MMS fails on iPhone 5 with AT&T when APN configuration profile installed
Installing a configuration profile containing APN information to the new AT&T iPhone 5 results in breaking the capability to send or receive MMS messages through the Messages app on the device. This is for MMS (Multimedia Messaging) and not iMessage (that works fine).
This happens regardless whether the device is on LTE mode or on 3G mode.
The configuration profile we are using has APN information and proxy settings for this APN as well (proxy host and port information). However, the problem happens even if the profile contains just APN without any proxy settings info.
This happens on iPhone 5 ONLY (commercially available through AT&T). This is important to note because iPhone 4S with iOS 6 DOES NOT HAVE THIS PROBLEM.
This problem happened last year too when iPhone4S was introduced. But it was fixed later.
iPhone 4S, iOS 5