Mexico

Movistar
Movistar is a major mobile phone operator owned by Telefónica Móviles. It offers GSM 900/1800 MHz (2G), UMTS 2100 MHz (3G) and HSDPA (3.5G) services.

APN settings
 * username: movistar
 * password: movistar
 * APN name: internet.movistar.mx

Telcel
Telcel is Mexico's largest mobile phone carrier, owned by América Móvil. Telcel launched its 3G (850Mhz Band) services. This is the 2nd 3G Wireless Network after Iusacell's 3G Nationwide CDMA2000 network, and then expanding to other cities to finally become a national 3G network which will reach more than 350 cities. Telcel's 3G network is based on UMTS / HSDPA technology.

APN settings
 * username: webgprs
 * password: webgprs2002
 * APN name: internet.itelcel.com

Iusacell
Iusacell is the third and first 4G mexican network

APN settings
 * username: iusacellgsm
 * password: iusacellgsm
 * APN name: web.iusacellgsm.mx

Telcel
After the first 100MB per day (1GB per week, 3GB per month), they may drop your speed down to 128kb. Doesn't seem to be a volume limit (although speed obviously limits the amount of data). It works in Mexico only.

How to top up
Refill cards are available from stores, Mexican bank accounts and ATMs can be used; there are also some US companies selling online recharges.

Where to buy
SIM cards are called (microchips) and can be brought from local Telcel dealers you'll find almost everywhere in the country.

Sim Sizes
Mini SIMs exist. Micro SIM availibility.

Movistar
MXN 0.02 per additional KB

Where to buy
Refill cards are available from newsstands, convenience stores,supermarkets. Customer service number is *611 dialing from a movistar cell phone.