Copied from the
MetroPCS Sticky thread:
Below is the standard APN for MetroPCS GSM
apn carrier="MetroPCS LTE
mcc="310"
mnc="260"
extraid="6D"
apn="fast.metropcs.com"
user=""
password=""
authtype="0"
server=""
proxy=""
port=""
mmsc="
http://metropcs.mmsmvno.com/mms/wapenc"
mmsproxy=""
mmsport=""
type="default,mms,supl"
preferapp=""
The T-Mobile one which is below is also known to work
apn carrier="T-Mobile LTE
mcc="310"
mnc="260"
extraid="6D"
apn="fast.t-mobile.com"
user=""
password=""
authtype="0"
server=""
proxy=""
port=""
mmsc="
http://mms.msg.eng.t-mobile.com/mms/wapenc "
mmsproxy=""
mmsport=""
type="default,mms,supl"
preferapp=""