I just bought the tab 3 7" T217A from at&t and went to Mexico to use it in 3g but I don't get any data access.
The tab recognize the sim card company (telcel) and the APN values are correct, it's Sim unlocked I suppose.
Pretty much all carriers in the US are locked to their devices. However, that should not stop you from data connections unless the host carrier does not have data or the host carrier uses different frequencies for data. It is also possible you may have to use EDGE and not 3G for your data. My iPhone 3GS worked in Afghanistan on GSM but I was limited to EDGE as they had no 3G. Just a thought. You should go to a local cell phone store and ask about data on the T217a.
Caveat: I do not know the Mexican network nor the device you are using. My comments are just based off of assumptions.
Yes, you are right, I had few phones that appears in edge but can connect tod data but in this case the signal icon appears just the bars but no E icon or roaming.
I think I'll go to a store to check it
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