SAN FRANCISCO (CBS SF) — Time is running out on the 415 area code and so are available 415 numbers, especially if you live in Marin County.

As of February 1, the new 628 area code ‘overlay’ goes into effect. Increasing consumer demand prompted the Public Utilities Commission to add the 628 area code to the region that has been using 415 since 1947. That’s San Francisco, most of Marin County, and a small portion of San Mateo County.

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If you already have a soon-to-be classic 415 number you get to keep it. But new 415 numbers are in short supply.

A T-Mobile employee in Marin County we spoke to said customers are concerned about getting a classic 415 area code.

“They are asking if there still are any, but we haven’t run out quite yet,” she said. “A lot of towns are out, though.”

San Rafael is out. San Rafael-ites won’t be assigned a 628 number. Instead they’ll get a classic 415 area code, but the prefix will come from some another town.

“Belvedere and Larkspur still have some,” she added.

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An employee at San Francisco’s T-Mobile store on Union Square said she had one customer come in actually requesting a 628 area code.

“Just one, though,” she said. “Our store caters mostly to tourists, and they don’t care.”

The T-Mobile store on 9th and Lincoln hasn’t seen any dramatic spikes, but said there are not many classic 415’s left in San Francisco either.

As things stand, starting February 21, 2015, all calls made from the 415 Area Code will have to be dialed using 1 + area code + 7-digit telephone number.

The official roll-out for new 628 area code numbers isn’t until March 21, 2015. So, what happens if we run out of classic 415’s before then?

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We reached out to the PUC to find out. They said they will get back to us about the contingency plan.