So you have a brand new unlocked android phone and you want to use a T-Mobile Prepaid sim card? Go to your Settings->Wireless and networks->Mobile Network->Access Point Names then tap properties and hit “New APN” and configure these parameters.
Name: T-Mobile
APN: epc.tmobile.com
Proxy: <Not set>
Port: <Not set>
Username: <Not set>
Password: <Not set>
Server: <Not set>
MMSC: http://mms.msg.eng.t-mobile.com/mms/wapenc
MMS proxy: <Not set>
MMS port: <Not set>
MMS protocol: WAP 2.0
MCC: 310
MNC: 260
Authentication type: <Not set>
APN type: <Not Set> OR Internet+MMS (depending on software version)