I just purchased a brand new G900V CDMA/GSM Unlocked Samsung Galaxy S5 to replace my current Samsung G900A S5 that freezes and has slowed down.

This is my 3rd S5. The first had a bad mic connection and even though I had a receipt from an AT&T store, Samsung would not honor it, and the second now is having problems after a year. I LIKE the S5, and I am hoping that the "third time is the charm." My wife's S5 has been flawless for 4 years!

The seller (ebay) said it was 4G Compatible on Verizon/Sprint/AT&T/T-Mobile on both CDMA and GSM.

I popped my AT&T Sim into it, and when it boots it has a Verizon screen of course, the says it is NOT a Verizon Sim, but then it finds the network and my WiFi, but the Text Message App appears to be a Verizon dedicated one that would have to be changed.

I dialed some telephone numbers and it seems to work fine, but...

Can anyone tell me what I need to do to make the phone act like an AT&T phone?

I did a little digging and supposedly it is 4G LTE compatible on AT&T, but I am an absolute neophyte and know nothing about these phones as far as re-configuring anything.

So ANY help, or a link that would help someone as clueless as me set it up would be much appreciated.

I ASSUME the seller was right about it being compatible. They had a bazillion sales and a 99,5% Feedback rating.

Thanks,
Bob