By Andria Borba

SAN FRANCISCO (CBS SF) — Intercom companies are scrambling to update systems in dozens of buildings around San Francisco now that the dialing procedure for the 415 area code has changed.

β€œSan Francisco was caught off guard,” Mark Greenspun of AAA Intercom Systems told KPIX 5.

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The new 628 area code means all calls within the 415 must dial eleven digits, adding a β€œ1-415” to existing numbers to buzz open the doors of San Francisco apartment buildings.

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The fix takes about an hour, and in the Tenderloin neighborhood alone there are some blocks with 20 now useless buzzers.

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β€œI had a building with 150 tenants and it took two of us two and a half hours to reprogram it,” Greenspun said.