We’re making the call: it’s the start of a new era.

The D.C. Public Service Commission announced Monday that the District’s new (771) area code will start being assigned to phones and services in the city starting on Nov. 9, indicating that after a solid run stretching over seven decades, the original and iconic (202) area code has been all but used up.

D.C.’s new (771) area code was announced last fall, kicking off a 13-month transition process spurred by the reality that the (202) area code — which was first introduced in 1947 — was running out of phone numbers. (Each area code can produce roughly eight million seven-digit phone numbers.) The new area code — which was assigned by the North American Numbering Plan Administrator, the official regulator of area codes in the U.S. — will be known as an “overlay,” applying to all new numbers regardless of location in the city.

And that will prompt another change that could impact some users: starting in October, all phone calls in D.C. will have to include the area code, even if one (202) number is calling another. “An overlay does not require customers to change their existing area code, but does require customers to dial the area code to complete local calls,” said the Public Service Commission in a press release.

Overlays have been used in Maryland with (301) and (240) and in Virginia with (703) and (571).

“Customers should ensure all services, automatic dialing equipment, applications, software, or other types of equipment are reprogrammed to dial 10 digits if they are programmed to dial just 7 digits, and recognize the new (771) area code as a valid area code,” the commission added. Examples include life-safety systems, fax machines, internet dial-up numbers, gates, ankle monitors, speed dialers, mobile phone contact lists, call forwarding settings, voicemail services, and similar functions, according to the commission. Customers should also check business stationery, advertising materials, personal checks, and personal or pet ID tags to ensure the area code is included in your telephone number.

What won’t change, though, is calls to 911, 811, 511, 311 and other such numbers — no area code will be needed for those.