Hi, I used to have a Locked At&t iPhone 4 with a straight talk At&t sim. Worked fine, had data etc. I was given a T-Mobile Galaxy S3. So i decided to switch to it instead. Got on straight talks website and bought the T-Mobile compatible micro sim. Used the website to switch my number from my iPhone. Changed the spn settings and now My GS3 says it has full service, yet when i try to make a call it says "Not Registered On Network". Cant figure this out. Any help?