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Technology & Innovation
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The Secret Mexican History of Area Codes 706 and 905
Did you know the area codes for North Georgia (706) and suburban Toronto (905) weren't always for those places? Until 1991, they were special codes used by Americans and Canadians to dial directly to cities in Mexico. This is the story of how an international dialing change gave them new homes.
If you live in North Georgia or the sprawling suburbs around Toronto, the area codes 706 and 905 are a part of daily life. They’re just numbers, a familiar prefix for local businesses and neighbors. But these seemingly ordinary codes have a secret, international past that connects them directly to Mexico City, Tijuana, and Acapulco.
The Old Way to Call Mexico
Before the internet and easy international calling plans, phoning Mexico from the U.S. or Canada worked differently. Instead of dialing the international access code (011) and the country code for Mexico (52), callers used a special, simplified system. You would dial 90, followed by a single digit representing a major Mexican city. For example, to call Mexico City, you’d dial 90-5 and then the local number. Tijuana was 90-3. This system was part of the North American Numbering Plan (NANP) but set aside specifically for this purpose.
Similarly, certain 70X codes were reserved for special services, including calls to Mexico. This unique arrangement meant that area codes like 905 and 706 couldn't be used for geographic regions in the U.S. and Canada—they were already taken.
A Global Shift and a Number Crunch
In the early 1990s, two major forces converged to change everything. First, the international telecommunications system was standardizing. Mexico was preparing to adopt the global standard, requiring callers to dial 011-52 to reach the country. This change, which took effect in 1991, would make the old 90-X system obsolete.
As Ralph A. Mamsmath, a director at Bell Communications Research, explained in a 1991 interview:
“It was a plan that was put into effect years ago for dialing to Mexico and for other international points. But it has been superseded by a new international dialing plan.”
Second, the demand for new phone numbers was exploding. The rise of fax machines, pagers, and second phone lines meant that North America was rapidly running out of available area codes. The impending obsolescence of the Mexico-specific codes was welcome news for telecom planners. Freeing up the 90X and 70X series would provide a fresh supply of numbers for growing regions.
From Mexico City to Georgia and the GTA
With the switchover complete in 1991, the once-reserved area codes were returned to the general pool. They were quickly assigned to areas desperate for numbering relief.
In 1992, area code 706 was officially established for a large swath of northern Georgia, including cities like Athens, Columbus, and Augusta. A year later, in 1993, area code 905 was born. It was created from a split with the iconic 416 area code, assigned to the massive, rapidly growing suburban region surrounding Toronto, often called the “Greater Toronto Area” (GTA).
So, the next time you dial a number in North Georgia or the suburbs of Toronto, remember its unlikely journey. It's a small piece of trivia, a relic of a bygone era in telecommunications when calling Mexico City was just a 905- away.