For travelers considering a trip to Mexico, "911" is now the official number for all emergencies there. This is a trend in several countries as they give in to the large number of users who consider "911" as the universal number for emergencies, regardless of where they are located. Mexico made the decision to switch to "911" in 2016 after wandering all over the keypad with multiple 3-digit numbers for various services. Now, "911" connects you to all Mexico emergency services: fire, ambulance, police, Red Cross and others.
For many years, most US phones operating in Mexico would automatically convert a call entered as "911" to the proper emergency number. Even that was a moving target. Now you press "911" from both wired and wireless phones. The decison was among those made as a result of the the mass kidnapping and murders in Iguala, Guerrero, Mexico on September 26, 2014.
We have added this tip to our Mexico Calling Procedures Page that you should consult before your next trip South of the Border. As in the US, don't save "911" in your phone's address book. It's the cause of the greatest number of erroneous 911 calls.