The APN settings for the T-Mobile Network. I'm in Dallas, Tx so not sure if my settings will work. I tried these settings on two phones the Xperia Z-Ultra and the Galaxy Note 3. The ZUltra was already unlocked. The Galaxy Note 3, I had to unlock it first. Both worked and received 4G LTE.
Here are the APN settings you can try: (make sure to remove the blanks from the link entry in MMSC)
Name: T-Mobile US
APN: fast.t-mobile.com
Proxy: <leave blank>
Port: <leave blank>
Username: <leave blank>
Password: <leave blank>
Server: <leave blank>
MMSC: http : // mms.msg.eng.t-mobile.com/mms/wapenc
MMS proxy: <leave blank>
MMS port: <leave blank>
MCC: 310
MNC: 260
Authentication type: <leave blank>
APN type: default,mms,supl
APN protocol: IPv4
APN roaming protocol: IPv4
Bearer: unspecified
MVNO: None