Samsung Galaxy Discover unlocked - won't work with ATT sim

[kmacsouris]

My husband is a truck driver and has a Bell Samsung Galaxy Discover. Currently, he uses two phones - one for in Canada (Bell phone) and a generic ATT phone.

I went and unlocked the Discover phone and tested it to make sure it was unlocked. I put my Telus sim card in it and it works fine. When my husband puts his ATT sim into the Samsung Galaxy Discover, he is getting invalid sim. I thought these phones were good to work with ATT when unlocked. It works fine with his Bell sim card.

Any ideas or is it just that it isn't compatible with ATT?

 

[AMOCO]

Maybe get a new AT&T sim card,And it should work on the AT&T network from what I was just reading.

 

[kmacsouris]

I just let him know that. He is panicking now because when he puts the Bell sim back in the phone, he is getting no service. I think it is time for him to use a more user friendly phone

Thanks for your assistance.