[cool cat2]

I recently got this phone from eBay unlocked (originally an at&t phone). I activated it at the AT&T store, but it kept saying SOS on the signal bar. I checked the IMEI beforehand and it said it was compatible with the carrier.
This phone was not activated with BIS, just a regular "unlimited everything" plan from AT&T.

The "advanced service rep" on the phone in the store said it was not a compatible device.

Is six year old technology really not compatible? I checked the bands on the phone and every one of them are compatible except the 4G (obviously). It even says Carrier: AT&T in the settings but I cannot figure out where to input any carrier settings besides the APN, which doesn't help that much.
I will be going to uBreakIfix tomorrow as recommended from the at&t store; however, I have my doubts on this working at all.

There is also little to no documentation on this issue so I am coming here. Any help or input is appreciated, thanks.

[Laura Knotek]

Did you get a BIS plan?