Thank you for this post! This should really be stickied! The information is very accurate and pretty much explains all of the current idiosyncracies of Mexican telecommunications to a T.
The only thing is that information about Iusacell would be helpful because there are contract-free plans where you just pay one month in advance where calls to any landline or cellphone in the US, Canada, and Mexico over the allotted number of minutes costs just 89 centavos or 6 US cents per minute.
If you pay 399 pesos a month you get, 1,400 minutes to anywhere in Mexico, the US, and Canada, 2 GB of Internet, and unlimited social networks. Any minutes over the limit cost about 6 US cents per minute.
If you pay 699 pesos a month you get unlimited calls to anywhere in Mexico, the US, and Canada, 4 GB of Internet, unlimited social networks.
I agree that Iusacell isn't a good option for the casual tourist, but this can be a good deal for anybody who lives in Mexico and will be within the coverage area. (Tijuana, Tecate, Mexicali, and Ensenada) Dealers can be found in most major shopping malls and in Zona Rio. Just like with Movistar, coverage is sketchy outside of the major cities.