Verizon Samsung Galaxy S3 (Unloocked) TRYING TO WORK WITH A&T

My siblings and I got a Verizon brand Samsung Galaxy S3 but this turns out to be one big pain in the ***.

When my mom and I got an new At&t SIM card from the store, it wasn't working well, and the signal kept on dropping (can't connect icon on top), but we saw few bars but it kept on dropping. When we did, we attempt to call one of our phone, no luck...we tried to figure it out in the store (At&t guy doesnt care, geee I wonder why...Verzion brand). So my mom and I decided to get out of these, try to figure it out at home. When we got home, i noticed that the signal strength has all bars most of the time, so try to call the home line, it worked. BUT when I noticed it was connected to 2G (Edge) only (maybe thats why in the store, it wont connect, due to lack of 2G signal) and noticed i cannot go online (maybe APNs thing). Data is on but ZERO data connection. So I am very stumped. We want to make this work If I don't figure this out, my brother will return it on Monday.

Summary.

1. Why is it only connected to 2G?
2. Why I cant connect to the internet?

Thanks guys

 

menu > Settings > More Settings > and from here I have to go from memory, since my S3 is no longer on a network, Mobile networks is greyed out...but in Mobile networks you should be able to specify the type of signal, meaning GSM or LTE/CDMA. hopefully, that'll be what you need

EDIT: if it's the same as the S5, your next choice is Network mode. there you should pick, for AT&T GSM/UMTS. if it's already that setting, you are probably stuck with poor data....

 

Sadly, I already did that (GSM/UTMS), still connected to 2G and no internet

 

only thing I can think of is Verizon pre-paid.....did you also try the global option?

 

From the very beginning, it was set Global.

Thanks RA for trying to help.

 

there's a discussion here, that may shed some light:
http://forum.xda-developers.com/showthread.php?t=1895684

 

I think my brother read that or similar. Anyway, my brother decided to return it.