For Kelli Parker and her husband, Andy Lippitt, finding a place to live in Manhattan was secondary to obtaining what they thought would instantly identify them as New Yorkers: his-and-hers cellphone numbers with 212 area codes.

The couple is preparing to move from Boston, and Ms. Parker did not want to get stuck with a number that started with 646 or 917 — the other area codes that will cover the borough until a fourth is added in a few years. To her, and others who recall New York City’s original first three digits, the only acceptable area code for a Manhattanite is 212.

“It’s New York City’s phone number,” Ms. Parker, 40, said. “It’s a status symbol most definitely.”

Even at a time when phone numbers have become as portable as the devices they identify, a number that begins with 212 is still in demand. And the odds of getting one free remain slim, even though New Yorkers have been abandoning their traditional home phone lines — all of which once had 212 codes — and using just cellphones at a fast pace.

In fact, cellphones have been proliferating in the city so rapidly that state regulators were notified on Friday that Manhattan will need yet another area code by late 2017.