Is the cell phone number a mexican number or a U.S number? If a Mexican number then you dial it with the international codes. If a U.S. number then you call it like you normally would, with the possible exception of putting a one in front of the number for an out of area call. However, if you are calling from another cell phone, you may not be able to call an international number if your plan does not allow it.

For international calling codes, you can usually look in the front of your local telephone directory. Assuming the access code to dial out of the country is the same for cell phones (011), the country code for Mexico is 52 and the city code for Monterrey is 8. Make sure you know how much the international charges are going to be before you try it, but to call Monterrey you should dial:

011-52-8-(local telephone number)

I have a friend who has a cellphone but I dont know how to dial it from the US. Does anyone know if what the phone code for Monterrey, mexico is? How can I get it?