From Canada and US
dial 011-52 + the number.

From Mexico on a non TelCel phone outside the 315 area code dial 045 + 10 digits.

From Mexico on a non TelCel phone in the 315 area code dial 044 + 10 digits.

From Mexico on a Telcel phone in the 315 area code dial only the last 7 digits.

From Mexico on a Telcel phone outside the 315 area code dial all 10 digits.