To my knowledge in seeking a replacement Net10 (TracFone) cellphone, whether or not they use a GSM or CDMA type depends on where you'll be predominantly using their service, as they use others' towers. They offer both types (CDMA doesn't use SIM cards, GSM does) but what I gather from one post here, their phones still won't work even if their SIM card is switched from one to another, if you haven't purchased the replacement from them too. Didn't have a response to my post about that yet, so I'll be looking FWD to any information re: SIM topic. But as my experience with Net10 (TF) has been so rosy (read: "flushable!"), I'm not that keen on getting a dedicated phone from them! Also not keen on a contract phone, either! Thinking of amateur radio about this time... any alternatives?