Staying connected while traveling or living in Mexico with a cell phone is not a problem. If you are bringing your domestic phone with you, call your manufacturer to see if your phone will be compatible with a Mexican SIM card. If your cell phone is not compatible, you can always purchase a Mexican cell phone.
You can buy a Mexican cell phone at any Telmex store or other store that sells cell phones like Sams Club or Costco. The low-end cost of a cell phone begins at about $350.00 pesos and usually comes with about 10 minutes of air time to get you started. You can purchase more air time at Telmex stores or convenience stores easily. Any OXO, Extra, Chedauri, Mega or even some small family owned stores have the ability to sell minutes.
Phones purchased in Mexico must be registered before you can use them. Ask the person who sells you the phone to help you register it, and make a test call before you leave the store. At the time you buy the phone, it’s best to have an official ID such as a passport, FM3, or driver’s license with you for registration purposes.
Dialing Cell Phones and Land Lines Within Mexico and Beyond
Not knowing how to dial land lines from cell phones, and vice versa, in Mexico can be frustrating and annoying. For a list of useful swear words, check the Spanish-English slang dictionary. Or, try the following:
To call the U.S. or Canada (cell or land line):
Dial 001 + area code + local number
To call other countries:
Dial 00 + country code + area code + local number
Calling from Mexico to US or Canadian Toll Free numbers:
For 800 numbers: Dial 001-880 – the seven digit number
For 866 numbers: Dial 001-883 – the seven digit number
For 877 numbers: Dial 001-882 – the seven digit number
For 888 numbers: Dial 001-881 – the seven digit number
Mexican cell phone to local land line:
For Your Wallet!
Local number only (7 digits except for Mexico City, Monterrey, and Guadalajara, where phone numbers are 8 digits)
Mexican cell phone to land line elsewhere in Mexico:
area code + local number
Mexican cell phone to cell phone, long distance Mexico:
area code + local number
Mexican cell phone from outside the country:
To dial a Mexican cell phone from outside the country, dial 011 (access code), 52 (country code), and then a “1” before the area code and local number. If you don’t add the “1” you will get a busy signal and may not realize that you’re dialing incorrectly. (e.g., 011521/415-152-0000.)
Mexican land line to cell in same service area:
044 + local number, including area code (e.g., 044-415/152-0000). On most monthly land-line phone plans there is an extra charge to call a cell phone in the same service area from your land line. If you’re calling from a hotel or other public place this service may be blocked, and you’ll get a busy signal.
Mexican land line to cell phone long distance within Mexico:
045 + area code + local number (e.g., 045-442/256-0000). On your monthly bill you will be charged per minute for this call.
Mexico is divided into nine service regions. If you purchase cell phone minutes in one service area you must upload them in the same service area. For example, if you buy minutes in Mexico City you must upload them before returning to Guanajuato, which is a different service region. Once you leave the service area where the air time was purchased, you cannot upload them.
Emergency and Useful Phone Numbers
These numbers work from a pay phone, land line or cell phone. There’s no charge to call.
066 or 061 (varies from place to place): Emergencies, police
065: Red Cross
078: Green Angels or tourist information
Charges may apply when you call these numbers.
020: Mexican operator
040: Information
090: International operator
Tricks of the Trade
It’s significantly cheaper to send a text message to your local friends than to call them on their cell or home phone. 
It’s about four times more expensive by the minute to use the pre-paid phone plan than it is to use a service plan, but pre-paid you’re saving the monthly fee. The monthly service plan provides the better option for people who use their cell phone on a regular basis, but for people on a vacation, or who live in Mexico and only use their cell phones sporadically, the prepaid calling plan is the best bet.
You can start with a pre-paid plan and watch your usage. You’ll have to figure the break-even point to know when it is best to switch.
You need to be careful when adding minutes to your pre-paid phone, or “top-up.” With Telcel, if you make an “electronic top-up” of $20, your new credit balance will last for 10 days. If you make an “electronic top-up” of $30, your new credit balance will last for 15 days. If you make an “electronic top-up” of $50, your new credit balance will last for 30 days. So, for example, your old balance is $250, after an electronic top-up of $20, your new balance of $270 will only last for 10 days before it is all lost, unless you make a new top-up sooner!
With any kind of top-up of $100, or more, the new credit balance will last for 60 days. On day 61, any remaining credit is lost. A Telcel telephone number remains active for 180 days after the last top-up.
Important to know: The person who makes the call incurs the charge, whether from a cell phone or land line: local, national, or international. Therefore, if you take a call on your cell phone from a person calling long-distance within Mexico, or even from outside the country, there is no charge to you IF YOU ARE WITHIN YOUR OWN SERVICE AREA. Outside your own service area, roaming charges apply.
Use it or lose it.
If you don’t use your cell for two months, your minutes disappear.
If you have lost your minutes after not using the phone for two months, but purchase more minutes before four months from your last phone call, you recoup your lost minutes.
If you don’t use your cell phone for four months, you lose your minutes permanently.
If you don’t use your phone for six months, you lose your minutes AND your telephone number becomes inactive. You must buy a new SIM card and re-register your phone. So even if you keep your phone for emergencies only, make a call or send a text once in a while to keep the phone active.
If you want to purchase a Mexican cell phone, you must choose among various providers. Here are the major providers:
Telcel: http://www.telcel.com/portal/contactanos/cacs/begin.do?mid=7100 for customer service centers
MoviStar: From a land line, 01800/888-8361; from your cell phone, *611; http://www.movistar.com
Unefon: www.unefon.com.mx.
IUSAcell: www.iusacell.com.mx