this doesn't answer anyone's post, but i thought i'd share. i came to straight talk with an at&t iphone 5. i had troubles with mms and all that, so i bought a straight talk iphone 5, which runs off the verizon towers. it was better, but i decided to return it and wait for whatever the next apple phone is. i called straight talk customer service, and they were able to send me a replacement at&t sim card so i could go back to the byod program.
as i understand it, although they're not selling at&t sims in stores, they are still available to customers who were using at&t through support.