909 Area Code Map and Boundary Guide: Cities, Counties, and 840 Coverage
By Elena Rostova
By 2018, the North American Numbering Plan Administrator (NANPA) determined that available central office prefixes in the 909 territory would deplete within three years. Rather than splitting the region geographically, a disruptive process requiring businesses to reprint collateral and update signage, the CPUC approved an overlay relief plan.
The 840 overlay area code officially launched on February 23, 2021. Under this model, existing numbers retained their 909 prefix, while brand-new service activations began receiving 840 assignments.
The practical change for residents and enterprises was the end of seven-digit local calling. To route calls through dual codes occupying the same footprint, telecommunications providers enforced mandatory ten digit dialing requirements. Any call made within the region, even to a business or neighbor on the exact same street, must include the area code followed by the seven-digit telephone number (e.g., 909-555-0144). Dialing 1 before the area code is required for wireline carriers, while mobile networks generally route the call automatically once the ten digits are recognized.
Importantly, local calling areas did not change. Dialing a number within your exchange using the 840 prefix does not trigger long-distance toll charges. A call that was classified as local under 909 remains local under 840.
Elena Rostova holds a Master's degree in Public Health Journalism. She covers groundbreaking medical research, holistic wellness trends, mental health awareness, and nutritional science.
