T-Mobile US 4G LTE 5G Internet and MMS Settings for iPhone 14, iPhone 14 Pro, iPhone 13 Pro, iPhone 13, iPhone 12 Pro, Pro Max, iPhone SE, iOS 15 iOS14 iPad.
T-Mobile iPhone APN Settings
In your Apple iPhone go to Settings -> Cellular -> Cellular Data Network -> APN and enter the following details
Cellular Data:
APN: epc.tmobile.com
Username: Blank
Password: Blank
LTE Setup(Optional):
APN: Blank
Username: Blank
Password: Blank
MMS:
APN: epc.tmobile.com
Username: blank
Password: blank
MMSC: http://mms.msg.eng.t-mobile.com/mms/wapenc
MMS Proxy: Blank
MMS Message Size: 1048576
MMS UA Prof URL: http://www.apple.com/mms/uaprof.rdf