Default [Q] SM-217S Question regarding phone status info

Hi, I recently bought a used Sprint Tab 3. It's a data sim card version but I only plan to use it for wifi. Previous owner did a factory reset. Everything works fine, I rooted it to get rid of bloatware, no sim notifications, sprint crap etc. However, when I go to settings -> about device -> status, it shows a user name, eg. "usersname@sprintpcs.com" plus a phone number, MIN, PRL, etc. Tablet shows as connected to 3G network even though there's no sim card. If I enable airplane mode and reboot, all the fields show up as unknown and mobile network as disconnected, however the username remains.

I believe that info is from the previous owner, but where is it stored? I'm guessing the tab is getting it from the network even though there is no sim card in it to authenticate it which doesn't make sense. Removing all Sprint related stuff does nothing. I tried wiping the whole tablet and flashing a beta CarbonRom that was in the forums and the info still shows up in the about device status. I flashed back to stock rooted. Only difference is that android 4.2.2 has the username option while kit kat doesn't. Since I had made a complete backup of the tablet, I wiped the efs partition just for the heck of it and rebooted. Interestingly enough it removed the Sprint boot animations and replaced them with stock Samsung ones. Folder was recreated by android. Everything else is still the same. I was expecting the tab not to connect to anything anymore but I guess not. For all the doom and gloom that is said about wiping the efs partition, I was a bit surprised that it didn't absolutely nothing. There wasn't even a nv_data.bin file in it (although my S3 is also missing this file for some reason too.)

Any suggestions? I was thinking about trying to contact the person that sold it me, maybe he hasn't taken the tab off his account yet or something. If anything I can just keep airplane mode on with wifi enabled, still wondering how the tab is getting that info. I'd rather not have anything of the previous owner on it.