Stopped by a local cell phone place in Nogales, AZ this past weekend and inquired about what does/doesn't work in Nogales, MX. What I learned was:

T-Mobile - officially has no service in Mexico, but their signal does extend quite a ways into Nogales, MX (I know it goes beyond Hotel Granada). They said T-Mobile was the most popular there for that reason. And since the signal is using a US antenna, there's no "international" calling involved.

Verizon - They have international calling available in concert with a Mexican phone company (Telcel?). Their phones can be used throughout Mexico, but it'll cost you 99 cents a minute.

I have had t-mobile for a while now...tucson # and have lived IN Nogales,Mexico for a year now.You are right about the service...right around the McDonalds(in Mexico) I loose service.Other than walking around a little saying "can u hear me now" in certain places the service works well for me.

Boost is Nextel's prepaid. Checkout Ebay for used phones - cheap and work great. Sometimes, problems indoors when you are away from the border. Outdoors work great at Burger King. 25cents a minute. No contracts. Not available in AZ, need to buy a registered phone in CA or NV. Or to there and get one.

bluelight, where are all the chica posts?? all you do now is just give info on cell phones and rental cars???

all the Nogi-philes suck at chica reports,
present company included