Telmex has almost the monopoly on call rates. Therefore, the price of international and national calls are very expensive. Local calls are relatively correct. Therefore, nowadays, communicating per email is sometimes not bad and at last less expensive.

Mexico's international code is 52. There are  public telephones all over the country, from where you can make national and  international calls, directly or via operator. Public telephones work with coins or cards (obtainable from stores). Don't be surprised if most of them accept only cards; coins are not very used, so it is always good to have a card at hand.They cost $ 20,00; $ 30,00; and $ 50,00 (Mexican pesos).

To make an international call from Mexico, you have to dial 00, then the country code, the city code, and finally the phone number. For national long distance calls, you have to dial 01, the city code and the phone number. You can find "prepaid cards" as well that will cost $50, $100, $200 (Mexican pesos). 

In relation to mobile phones, if you want to call one of them from the same city, you must dial 044 first, the city code and  the phone number. If you are in another city, or abroad, you must dial as if you were calling to a normal phone.