Which AT&T phone has the best reception / strongest antenna?

I am trying to figure out which AT&T phone out there right now has the strongest internal antenna. We are trying to replace my dad's super old cell phone with a new one, but he is worried that the new one will not get the same reception out in the rural area where he has to use it. I know the sales reps say that all the phones are the same, but that is not true. My Sony Ericsson will not work where my dad's current Motorola phone will, and we are both on AT&T. Any recommendations anyone? The only requirement is that it needs to be an easy-to-use flip phone that is somewhat rugged. He does not text, take pictures, access the internet, etc. Thanks for the advice!

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› See More: Which AT&T phone has the best reception / strongest antenna?

I have been told the Samsung Galaxy SII has the best. I do have this phone and we live way out where there isn't much service. My boyfriend has the HTC Inspire and it gets nothing any where except 4 bars of H+. The Iphone 4 did ok but my Galaxy does great.