I purchased an iPhone 6s direct from Apple.com and purchased the phone outright. I use Straight Talk (AT&T MNVO). I put my Straight Talk sim in, and I don't see the Cellular Settings in the Settings Menu. Is my phone not unlocked? I removed the Tmobile SIM before powering it on. I put in my Straight Talk SIM, plugged it into my computer with iTunes, and powered it on. It never showed the "Unlocked" message that others reported. Is my phone not unlocked? Am I screwed?