i have to keep restarting my phone

[Android Question]

I bought a unlocked galaxy s3 for straight talk, I purchase a activation kit with new sim , I activated it and my phone and internet keeps going off and I have to restart my phone like 5-8 times a day it is only my second day with it...

 

[Rukbat]

Which model S3 (by number) and AT&T or TMobile ST SIM? (Unlocked means it'll accept either SIM, it doesn't mean it has the radios to use that company's towers.)