The 424 area code blankets the west side of Los Angeles County — Santa Monica, Beverly Hills, Malibu, Culver City, Inglewood, Torrance, the beach cities, and Catalina Island — as an all-services overlay of the 310 area code, carrying calls since August 26, 2006.
Puzzled by a 424 number on your screen? It marks a west-Los-Angeles line — the same Westside territory as 310 — but the readout by itself says nothing about who is actually calling.
424 at a glance
| Quick fact | Answer |
|---|---|
| In service since | August 26, 2006 |
| Overlay | 424 is itself an all-services overlay of 310 |
| Territory anchors | Santa Monica, Beverly Hills, Malibu, Inglewood, Torrance |
| Dialing | 1 + ten digits, mandatory since July 26, 2006 |
| Exhaust projection | First quarter of 2043 for 310/424 (NANPA, April 2026) |
Most area codes get created once. This one was created three times. NANPA first assigned 424 to the Westside in 1998, watched California shelve it a year later, saw it redrawn in 2000 as a split code that would have renumbered the South Bay, and finally put it in service in 2006 — the first overlay California ever switched on. The eight-year paper trail is a short course in how the numbering plan actually makes decisions.
Assigned in 1998, silenced in 1999
The Westside’s number crunch predates the code itself: 310 was already in jeopardy under Bellcore’s PL-NANP-054, and on April 24, 1997 the California-Nevada Code Administration applied what NANPA’s paperwork calls “special and extraordinary” conservation measures. The CPUC answered with Decision 98-05-021 in May 1998, ordering an all-services overlay, and NANPA’s Planning Letter PL-125 (May 26, 1998) published the schedule: mandatory 1+10-digit dialing on April 17, 1999, with the new 424 code opening for service on July 17, 1999. A test number — 424-654-0424 — was booked to start answering that June.
Westside subscribers never dialed it. Resistance to ten-digit dialing and to a second code on the same streets ran hot enough that the Commission changed course: Decision 99-09-067 suspended the authorized 310/424 overlay and swapped in number pooling and related conservation measures to stretch the supply 310 still had. The full fight is told from the incumbent’s side in our 310 area code guide; what matters here is what it left behind — a fully assigned area code with no subscribers, parked.
The split that would have moved 424 south
The second version of 424 looked nothing like today’s. In Decision 00-09-073 (September 21, 2000) the CPUC adopted a two-way geographic split as a back-up relief plan, and NANPA’s Planning Letter PL-250 (November 10, 2000) drew the line: communities across 310’s south — Avalon, Carson, Compton, El Segundo, Gardena, Hawthorne, Inglewood, the beach cities, Torrance, San Pedro — would change to 424, while Santa Monica, Beverly Hills, and the rest of the north kept 310. That letter formally superseded every earlier overlay plan for the code.
The split carried a fuse instead of a date: implementation waited on an independent audit of carrier utilization data and on a finding that 310 sat within eight months of exhaust. The fuse never lit. Pooling kept working, and Decision 03-10-060 (October 16, 2003) concluded a split still wasn’t necessary — the supply just needed monitoring. Had the trigger fired, Torrance and Catalina Island would hold 424 numbers today and Santa Monica would not.
Third plan, first California overlay
Decision 05-08-040 (August 25, 2005) finally settled it: the split plan was rescinded and an all-services overlay — the arrangement approved back in 1998 — was ordered into effect. CPUC President Michael Peevey marked the moment plainly, calling it the first time this form of area code relief had ever been used in California. NANPA’s Planning Letter PL-347 (September 8, 2005) replaced both of its predecessors and laid out the countdown.
Permissive 1+10-digit dialing opened December 31, 2005; mandatory dialing arrived July 26, 2006; and the first 424 prefixes could activate on August 26, 2006 — the code’s official birthday, eight years and three months after its first planning letter. Carriers checked routing against a self-describing test number, 424-424-0424, live from November 2005 through September 2006. Our area code guide gets into why regulators now reach for overlays instead of renumbering half a city.
The map and the dialing drill today
PL-347 defines the shared 310/424 footprint as the western portion of Los Angeles County: Santa Monica, Beverly Hills, Malibu, and Culver City on the Westside; Inglewood, Hawthorne, Gardena, Compton, and Lynwood inland; El Segundo down through Torrance and the Palos Verdes peninsula along the South Bay; LAX; Avalon on Catalina Island; plus small slices of Long Beach and West Hollywood. Downtown belongs to 213 and 323, the San Fernando Valley to 818, and Long Beach proper to 562.
Every call in the overlay area — local or toll — is dialed 1 plus the ten-digit number, the plan PL-347 put in force with mandatory dialing in 2006. Because of that early switch, the 988 crisis-line conversion had nothing to do on the Westside: NANPA’s PL-556 listed nine California codes that had to abandon seven-digit dialing in 2021, and neither 310 nor 424 was among them. The pair’s dialing rules haven’t moved in nearly two decades.
Numbered through 2043
Supply, once dire enough to invoke jeopardy procedures, is now the quiet part of the story. The 2026-1 exhaust study NANPA published in April 2026 puts the combined 310/424 prefix pool at exhaust in the first quarter of 2043 — a full ten quarters past the October 2025 call — and the four entries revised in the July 6, 2026 delta were all Texas complexes, so the Los Angeles pair stood as printed. NANPA’s relief-planning status report carries no 310/424 entry at all: no jeopardy, no rationing, no relief project on file.
Two codes, one Westside market
For a business dialing into west LA, the pair works as one market: a 424 display is exactly as Westside as a 310 one, and because 310’s long-held prefixes are the scarce side of the pool, new assignments mostly draw from 424 stock. The local presence math — matching your caller ID to the customer’s code — works identically with either. The caveat is the one every recognizable code carries: caller ID spoofing can borrow the digits, so the readout by itself says nothing about who is actually calling.
SIPNEX provisions Los Angeles DID inventory by specific rate center across the 310/424 footprint, pairs the number with hosted extensions from $6.99/mo, and delivers it over SIP trunking into the phone system your operation is built on — every outbound call signed A-level under a STIR/SHAKEN certificate SIPNEX holds in its own name.
424 area code: the usual questions
What part of Los Angeles does the 424 area code cover?
The western side of Los Angeles County, identically with 310: Santa Monica, Beverly Hills, Malibu, Culver City, Inglewood, Hawthorne, Compton, El Segundo, the beach cities, Torrance, the Palos Verdes peninsula, LAX, and Avalon on Catalina Island, plus small portions of Long Beach and West Hollywood. Downtown LA uses 213 and 323 instead, and the San Fernando Valley uses 818.
How do I dial a 424 area code number?
Dial 1 plus all ten digits — 1-424-NXX-XXXX — whether the call is local or toll and whether you’re calling from a 310 or 424 line. That 1+10 pattern has been mandatory across the overlay area since July 26, 2006, under NANPA Planning Letter PL-347. Because the Westside was already dialing ten digits, the 2021 conversion for the 988 crisis line required no changes in 310 or 424.
Was 424 almost a geographic split instead of an overlay?
Yes — after the 1998 overlay was suspended, CPUC Decision 00-09-073 rebuilt 424 as a split code. The southern reach of 310’s territory, from the beach cities and Torrance through Carson and San Pedro, would have given up its numbers and renumbered into 424, per NANPA Planning Letter PL-250 (November 2000). A 2003 review found the split unnecessary, and the 2005 overlay order rescinded it — so when 424 finally launched, no existing number changed.
Will Los Angeles need another area code after 424?
Not for a long while. NANPA’s April 2026 exhaust tables give the shared 310/424 prefix supply until the first quarter of 2043, ten quarters beyond the forecast before it, and the July 2026 revision cycle left that date alone. The pair appears nowhere in NANPA’s relief-planning status report — no jeopardy declaration, no prefix rationing, no open relief project. When exhaust eventually approaches, the standard fix would be a third code overlaid on the same map.
Do LA customers treat 424 numbers differently from 310?
Mechanically there is nothing to treat differently — identical footprint, identical rates, calls between the two are local. Perception is the only gap: because 310’s prefixes are the scarce, long-held ones, a 310 display can read as an older line while 424 reads as a newer one. In practice both are recognized as Westside numbers, and a 424 line in Manhattan Beach is every bit the neighbor of the 310 line next door. A carrier that provisions by rate center — like SIPNEX’s DID service — can tell you what 310 stock, if any, a given rate center still holds.
Whether the Westside line on your caller ID starts with 310 or 424, SIPNEX provisions it as an FCC-licensed carrier — local DIDs in every US market, RespOrg toll-free when a campaign needs it, and dialer-grade SIP trunking with each call signed under our own STIR/SHAKEN certificate. The number to dial is (833) 665-2220, the contact form reaches the same team, and rates are public.
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