New York City’s iconic 212 area code is featured in a Seinfeld episode. Rapper Pitbull named his record label Mr. 305, Inc., in an homage to his South Florida origins. A beautiful and talented bar manager in South Beach (hi Kat) incorporates her former and current hometown area codes (718 and 305, respectively) in her social media user names, elegantly and succinctly hinting at her cultural identity. Area codes (some of them, at least) have developed their own character and have become treasured cultural identifiers for many of us. And their history is fascinating.
When three digit area codes were originally implemented in the late 1940’s, the overarching design objective was to minimize the time required for hardware resources (mostly electromechanical switches and relays) to complete each telephone call. Two design decisions made at that time and for that reason resulted in the eventually iconic area codes we know and love. One was that the second digit of all area codes would be a 0 or a 1, and the second digit of all exchange triplets (the first three of the seven local numbers) would never be a 0 or a 1. This design permitted the switches to recognize whether an area code or an exchange triplet was being dialed as soon as the second number was entered, so they “knew” how many more numbers to expect and were able to complete each call (and be available for the next one) faster.
The other decision was based on the rotary dial systems of the day. The time it took for numbers to be dialed was proportional to the number itself; for example, on a rotary phone it took much longer to dial a 9 than to dial a 1. From the same Wikipedia article linked above:
The densely populated areas of New York City, Chicago, Los Angeles, and Detroit had large incoming call volume and were assigned the shortest area codes (212, 312, 213, and 313, respectively). A sparsely populated area of rural Texas received area code 915. Area codes which covered an entire province or state received the less-desirable '0' middle digit.
At that time, given the second digit convention, to reach a number in your own area code you only needed to dial 7 digits (the only exceptions were local “toll” calls). And, to dial across area codes, you would dial the area code plus the number (10 digits).
Later, beginning in the 1990’s:
The demand for telephone numbers was increasing rapidly, and the remaining n0n and n1n combinations were insufficient to sustain growth. This area code scheme was abandoned, with the result that area codes and central office codes could not necessarily be automatically distinguished by the switching equipment. The solution was to require the dialing of a preceding 1 for calls across area codes, in which case the equipment expected 10 more digits. If the first digit dialed was not a "1", only 7 digits were expected and the area code was inferred from the originating subscriber's area code.
Younger readers may be scratching their heads in puzzlement regarding the preceding “1” described above. It only applies to land lines, not mobile phones. Since cell phones send the entire number to the network at once, not one number at a time like land lines do, the preceding “1” was never necessary for them.
More recently, due to the proliferation first of fax machines and later of cell phones, more numbers were needed than could be sustained by the system, so more area codes were added (instead of adding more digits to phone numbers). In some cases, existing area codes were “split”. An example is South Florida, where the area code 305 initially covered both Dade (now Miami-Dade) and Broward counties, but in 1995 was split, and Broward County was assigned the area code 954. The splitting of area codes was widely criticized due to the cost to businesses of updating stationary, business cards, etc., so most of the following area code additions were implemented not by “split” but instead by “overlay”, where the area code in operation would continue for existing numbers, but new numbers would be assigned with the new area code. Again, South Florida provides an example, as the area code 786 was “overlaid” on the 305 region in 1998. In New York City, both 917 (in 1992) and 646 (in 1999) were “overlaid” onto the 212 region.
I have no doubt that because of area code overlays, and, more significantly, the fact that these days we typically select contacts instead of manually entering telephone numbers into keypads, the iconic nature and cultural significance of area codes will inexorably wither away. Who knows, telephone numbers themselves may soon be abstracted away by our communication devices the way IP addresses are abstracted away by our browsers and the magic of DNS.
Sadly, 212, 305 and their ilk will mean nothing to our grandchildren.