i have a at&t 1520. i went today and purchased a straight talk byop sim kit. inserted the nano and went through the steps. i got invalid sim. i went to the micro sim and cut it down. the 1520 reads no service now. not sure if its reading the sim. or what i really need to do. cant get any help from straight talk. i cant call anyone, dont have a phone. any and all help wold be greatly appreciated. i am new to windows phones but not electronics. pretty tech savy, but not really sure what to do next?