Dialing a toll free number north of the border from Mexico will not work

Calls to a toll free (also known as freephone/freecall) number are paid for by the receiver of the call, making them free for you, the caller. However, when dialing such a number from another country, you (the caller) will be charged international rates. So the call is no longer free when dialed from abroad. This is the reason why some long distance carriers/toll free number owners choose to block receiving international calls and generally advise their international callers to contact them on a regular telephone number.

To dial “toll free” calls to the USA or Canada, you must replace the 800, 866, 877, 888 prefix in the toll free number as shown in the table below:

So, for example, to dial AT&T Wireless customer service in the USA (800-947-5096) you would dial from Guayabitos using either a landline or cellphone: 001-880-947-5096. These calls are not really toll free, you will pay around 50 cents/minute for the privilege of being able to access these services, depending on what type of service plan you have.

I know that some people wish to continue using their cell phone from home but if you are visiting for a long period of time, you can buy a Mexican SIM card (if your cell phone uses SIM cards) and receive incoming calls for free as well as pay a lower, flat fee to make calls to the United States.

Land line to land line in same city (example: La Penita to Guayabitos)
Prefix needed: No prefix, no area code             Complete dialed number: 274-xxxx

This is the simplest option anywhere. The caller pays $1.5 pesos per minute plus IVA. A house Telmex phone line will get the first 100 calls per month free. A business Telmex phone line pays for every call.

Land line to cell phone in the same city (La Penita to Guayabitos)
Prefix needed: 044                                   Complete dialed number:  044-322-123-4567

As an example, the price per minute from Telmex to Telcel is approximately $1.84 pesos plus IVA.

Land line to cell phone in another town (La Penita to Bucherias)
Prefix needed: 045                                   Complete dialed number: 045-322-xxx-xxxx

This will be a long distance call from your landline and the calling phone will pay the entire cost of the phone call. The cell phone will not get charged for the long distance call.

For example, if the Telmex land line is 327-xxx-xxxx and you are calling a cell phone based in Bucherias, you will dial 045 322-xxx-xxxx. If this call is from a Telmex landline to a Telcel cell phone, it will cost $2.85 pesos per minute plus I.V.A.

Land line to land line in another town (La Penita to Guadalajara)
Prefix needed: 01                             Complete dialed number: 01-333-xxx-xxxx

This is larga distancia automatica nacional (automatic national long distance) and you will dial 01 before the area code and the phone number. The caller will be charged about $4 pesos during the day and $2.50 pesos at night for this phone call (without a special larga distancia plan).

Cell phone to cell phone
Prefix needed: None                         Complete dialed number: 322-xxx-xxxx

To call a cell phone from another cell phone, regardless of where the person is located at the moment, just dial the area code and the numbers without a prefix. The caller pays, and the cost depends on the plan. The cheapest Telcel cost for this type of call is $1 peso per minute; an Amigo card charges $2.5 pesos per minute plus IVA for the same call.

Cell phone to land line in the same town (Guayabitos to Guayabitos)
Prefix needed: None                 Complete dialed number: 322-xxx-xxxx or simply xxx-xxxx

You can either dial the area code and the 7 numbers or just the seven numbers. The price will depend on your plan. It can range from $1 peso plus IVA to $2.50 pesos plus IVA per minute. If you have an Amigo card, and you call a land line, you will be charged $4 pesos plus IVA per minute. The caller pays.

Confused yet?  The easiest thing to do while still learning the Mexican system is to write down the format, and refer to it as needed- I still do.