My data will not work on my iphone 5?

I bought my iphone5 off of a good friend. She had AT&T before, which is what my carrier is, and it worked fine with her. I have already been to AT&T. They told me to do the same things I had done already. Then, they called technical support to fine out what was going on, they said everything was fine with my network and all that. Can anyone tell me what the heck is wrong with my data?

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Have you already tried changing the APN settings?

Visit: http://www.unlockit.co.nz/ on your iPhone

Name: ATT
APN: wap.cingular
Proxy: none
Port: none
Username and password are blank
Server: none
Mmsc: http://mmsc.cingular.com
Mms proxy: wireless.cingular.com
Mms port: 80
Mcc: 310
Mnc: 410
Authentication type: none
APN type: default

Give us some more information.