I think the majority of people use Telcel. I do so without problems. My specific phone is a Samsung which I got in the US. The only trick is that you have to obtain the SIM Unlock Code from your service provider. You do this by calling customer service and telling them that you need to be able to use your T-Moblie, Cingluar or whatever phone in Mexico, where you have a local service provider. In 24-48 hours they email you the code and the instructions for entering it. Without this, your US phone will not operate with any other carrier. In Mexico you can then go to Telcel, tell them that you have a phone and just need the chip. You may want to go ahead and get the low end phone that they give new customers and that way you have a backup should your phone have a problem. The vast majority of people buy the prepaid service as opposed to a monthly plan. You can buy the scratch off Amigo cards anywhere, including at busy intersections. They come in 100, 200, 300 and 500 peso values. The more expensive the card, the more bonus credits you get. You get 100 credits for the $100 card, but 900 for the $500 card. You have 60 days to use your credits or they expire. But if you have credits that are about to expire simply buy and load another card and all of your credits are now good for another 60 days. What I do, since I travel back and forth regularly to the US is to simply switch my chips when I am on the plane. When I am in the US, for example, I keep my Telcel chip in my backup phone. When on the plane, my T-Mobile chip goes to the backup phone. This way the chips are in no danger of getting scratched or whatever and it is harder to lose a whole phone than a tiny chip. I hope this helps a bit.
