South Bay area code overlay starts in October

Starting in mid-October, anyone calling the South Bay from a phone with a 408 area code will be required to do something that may feel redundant: dial 1 plus 408 before punching in the remaining seven-digit phone number.

Due to Silicon Valley’s burgeoning population, a second area code — 669 — is set to be “overlayed” on top of the existing 408 area code region, according to the California Public Utilities Commission’s website. After Oct. 20, anyone calling a 408 number from another 408 number without dialing all 11 digits will be greeted with a recording reminding them about the change. Callers who do not key in the extra numbers will still be connected during a six-month grace period.

“The 408 area code, covering primarily Santa Clara County, is forecast to require a new area code by the fourth quarter 2012,” according to the CPUC. The new 669 area code was deemed necessary because all of the available 408 numbers were expected to be assigned by the end of the year.

According to the CPUC, no one with a current 408 number will be asked to change their area code. However, beginning in November, those living within the 408 area code and seeking a new phone number will be assigned one with a 669 prefix.

The 408 area code comprises the cities of San Jose, Campbell, Cupertino, Gilroy, Los Gatos, Milpitas, Monte Sereno, Morgan Hill, Santa Clara, Saratoga, Sunnyvale and a portion of Palo Alto, along with other smaller municipalities, according to the CPUC.