A typical telephone number in the San Diego area consists of ten digits. These digits are structured as a three-digit area code, followed by a three-digit central office code (or prefix), and finally a four-digit line number. An instance of this format might appear as 619-555-1212, wherein “619” designates a specific region within San Diego County.
The standardized North American Numbering Plan (NANP) dictates this structure, ensuring a consistent method for routing calls. This format allows for efficient allocation and management of telephone resources. Historically, the area code indicated a geographic region, but evolving communication technologies and population growth have necessitated the implementation of additional area codes to meet demand.