So i made the jump...left verizon for at&t and just picked this phone up on tuesday. Being my 3rd android phone this is by far and away the best i've had. Ive had one slight issue and its happened twice now. I found while i'm at work (not the greatest signal) my phone will show that i am connected via 4g hpsa but nothing happens. I cant make a call, send text, or check voicemail, surf web....nada...It shows 2 or 3 bars but if i try and make a call i hear nothing, its almost like the unit gets hung up. Then i restart the phone and it seems to resolve the issue.Its happened twice now, kinda weird. Also i noticed one the other day i was hooked up via wifi at my house with a great signal but couldnt do anything web related...Im not sure if this is the wifi issue people have been talking about. Is there any number i can call to make sure im connected to the best towers, like i remember on verizon you could dial *228 and it was kinda like a diagnostic call...Any ideas or help would be great