408zip Site The stands as more than a mere telecommunications prefix; it is a geographic and cultural identifier for Silicon Valley , the global epicenter of technology and innovation. Serving the southern portion of the San Francisco Bay Area, the 408 region encapsulates a transformation from agricultural "Valley of Heart's Delight" to a hyper-connected digital powerhouse. 1. Historical Genesis and Evolution The 408 area code was established in as a split from the original 415 area code , which previously covered most of Northern California. 408/669 Area Code - California Public Utilities Commission 408zip