Hi,
I had an AT T iphone 5s that I bought in the US on contract, which I had unlocked almost a year ago. I used it successfully in India with a sim card and internationally as well. I just got back and have been trying to get a SIM card to use it in the US. I have tried Ting and T Mobile. The networks show up, but when I try to make a call, I get the following message - 'The service you are attempting to use has been restricted or is unavailable. Please contact customer care. Message ca26065.'
Why is this happening? My India sim card still works on international roaming.