Here are the working APN settings I have for straight talk att phones (I have the samsung galaxy s3).
Name: STRAIGHTTALK ATT
APN: tfdata
Proxy: Not Set
Port: Not Set
Username: Not Set
Password: Not Set
Server: Not Set
MMSC: http : // mms_tf . net (no spaces)
Mutimedia Proxy: mms3 . tracfone ...
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