I live in Cornelia,GA 30531 and the coverage specifically at my home. I get zero to no reception. Not only me, but everyone who comes over and their with AT&T. I have tried Mark the spot app, but it practically does nothing when I had my iPhone. Now I have S3 and the app isn't even compatiable with the device. Please come fix this problem I can careless about the app thats why I turn to forum. Some of my friends who are on other networks get 4G or 4G LTE and others with AT&T get zero to no service. At the most we'll get the infamous G symbol the it would quickly switch to E then disappear.
I apologize you have having service issues at your house, I have had similar problems in the past in my own house and it's rough not getting phone calls. There is a solution with the AT&T MicroCell if you have High Speed Internet in your house. This would give you a mini-cell tower in your house full bars!
Mark the Spot should be compatable with your S3. If there is an issue with it, try to unstall the application, or reset the Google Play Store. Sometimes if the Play store is not working properly, it can cause app problems.
*I am an AT&T employee and the postings on this site are my own and don't necessarily represent AT&T's position, strategies or opinions.
So I looked up what a microcell is and it looks good however, I can't believe their is a price on this product for a service that I'm already paying for. I would expect AT&T would provide coverage within my area or at least upgrade their towers to do so.The price tag of $150 for microcell is not worth it in my opinion. Other service providers such as Sprint and Verizon have better service in my area. Sprint especially because now people are getting 4G LTE. If there's no other options then I guess I'll just wait it out until my contract ends and close my account.