I have it on AT&T and it works great, i drop a call every now and then. But my wifes iphone 4s drops calls in the same spots so i know it's not the phone, just at&t's crappy network. You have the latest firmware right?
I'm thinking it's your network location or a bum antenna on yours. My S3 has been equally good if not better than any of my previous (Motorola) smartphones. Never dropped a call yet. I thought I did one time, but it was the guy on the other end accidentally hanging up.
i just got my SIII that replaced my SI and the amount of dropped calls is ridiculous. my commute is 35 miles pretty much a straight shot and my SI never dropped a call. Today my new SIII droped my phone call to my wife 5 times. the signal would drop to no bars and i would get a circle with a line through it saying no signal. im thinking it has to do with 4G, my old phone was 3g and edge. my carrier is tmobile.
My SIII had no signal or no service more times that not any more. My HTC bolt never has a no service in 2 years of use and I get it about 5 times a day with my S III. Standing in one place I will have no service when I try to make a call then 3 bars and back to no service with out even moving in any direction. Phone worked great the first few weeks in my house now I have no service or 1 bar at best now and takes forever to get a phone call to go out. Takes maybe 3 minutes to get it to dial the numbers sometimes at the house now. Really dissapointed in the cell service with verizon and this phone.
My coworked finally had to get rid of his S3 and switch to the RAZR MAXX because of the unacceptable level of dropped calls. Now he never drops them. I personally think it was a phone problem, based on the fact that my Galaxy Nexus never drops a call in the same general areas...
I guess it could be bad phone or SIM. I have dozen of friends with GS3 (both at&t, verizon) around me and none of them is having call issues like this thread.
But I agree that Moto is safer bet on call quality than any makers. I got Razr HD mainly for 4G battery life and screen looking like Gnex, not the call quality reason. I didn't have any serious call issues with Gnex on verizon, but I can see why Moto is getting high remarks on that.