Have had Boost for almost a decade now. Never had to try their customer service til this one. Hint- it sucks. Maybe Dish fired a bunch of people, nothing on their voice lines but endless options that lead to no one. No chat that I can find. They do have a consumer board but lots of the questions look like they go unanswered. I've set foot in their stores and find them scary, besides I got the phone at a better price direct and I don't feel right about that. So this is the post I made to the Boost user board. Thought I'd repost here just in case. To repeat: the phone runs fine without the sim, but I suspect I'm forgoing any access to the T/Mo GSM towers and God knows what's going to happen to the Sprint CDMA stuff which is non existant in rural America anyway. "Got my new LG51 yesterday. Working fine. This morning I looked at the bottom of the box and saw the SIM card tucked in a flap. Envelope says Important. I assume this is used to broaden my coverage to TMo's GSM. Can I put it in after the phone is activated or will that do irreparable damage?"