The old 213 and 323 boundary no longer separates them
The California Public Utilities Commission says the boundary between 213 and 323 was eliminated in 2017. They now serve a combined overlay region, joined by 738. A 323 prefix alone is therefore not proof that a number comes from outside downtown Los Angeles.
Distinguish the wider Los Angeles market
The central 213/323/738 region is one part of a larger metro area. California also lists 310/424 and 818/747 overlay groups. Compare the codes associated with your actual office or service territory rather than treating every Los Angeles-area code as geographically interchangeable.
Choose for production, client services or local storefronts
For a production contact, test how the number appears on a call sheet and how easily a crew member can repeat it. For a storefront, try a window-sign layout. For a client-service business, test the receptionist greeting. These are practical selection exercises, not promises of better response rates.
Keep a stable number when projects change
Decide whether the number belongs to a company, an individual or a project before printing it on materials. Record who controls the receiving carrier account. Ask the service provider about routing and access if several coordinators will answer it.
Compare the complete number
Use the 213 market report for aggregate listed-price context, then compare actual numbers across your preferred codes. A pattern in another overlay may fit your use and budget better. Complete the port and test calls before updating call sheets, listings or advertising.