Everyone please listen. If you have a unlocked Nokia lumina 900 and T-mobile service you will have data and MMS problems when TMO go to LTE. DO NOT FRET. Here is the solution. 1st down load the Nokia network setup app. 2 load the following APN in both the internet APN and the MMS APN locations
fast.t-mobile.com 3 on the MMS apn there is a setting for MMSC Server you must add the following
http://mms.msg.eng.t-mobile.com/mms/wapenc DO not use
epc.tmobile.com as the MMS apn it will not work since the device is now on LTE.