310 Area Code + 424 Overlay = 11-Digit Dialing Every Time

Hold the phone, 310 folks--yet another new area code is headed your way.

But there won’t be any painful splits this time. Instead, the 310 area code will be the first region in the state to learn the ins and outs of the “area code overlay.”

For the most part, this new concept will affect those who live, work or make phone calls from within--and of course, into--the 310 area code.

This area code covers the South Bay and Westside regions of Los Angeles County, as well as a small part of Ventura County. Among the affected cities and communities are Catalina Island, Compton, El Segundo, Gardena, Malibu, Redondo Beach, San Pedro, Santa Monica, Torrance, West Los Angeles, Wilmington and portions of Beverly Hills, Culver City, Hawthorne and Inglewood.

With the overlay approach, there is no contentious carving up of the existing 310 region to saddle a designated portion with the new area code--a by-now very familiar process called a “geographic split.”

Instead, the overlay allows the entire region to keep its existing area code. The new area code--424 in this case--will cover the same geographic area, with 424 numbers issued as 310 numbers run out.

The good news: Code-weary residents and businesses need not fret over the cost and inconvenience of switching area codes and printing up new business cards or letterhead. The bad news: Everyone in 310 must begin dialing 11 digits (1+area code+XXX-XXXX) for every call--even those within the same area code.

The cost of calls, which are based on time of day, duration and distance, will not be affected by the addition of the new area code.

However, callers will have to reprogram auto dialers, fax machines, alarms, speed dialers and private corporate phone systems to recognize the new code and complete calls using 11 digits.

“The major point with an overlay is that dialing patterns change,” California Code Administrator Doug Hescox said. “No one will change their phone number. But what changes is how you will be dialing those numbers.”

The 424 code will be introduced gradually. Starting this month, callers could begin dialing 11 digits to make calls within 310 or continue to use the seven-digit method. But after April 16, all callers will be required to use the 11-digit number when calling within the 310 and 424 code region.

Those who misdial will hear a recording that instructs them to add “1” and the area code. The recording will be permanent to ensure visitors and newcomers are not tripped up by the overlay.

Phone companies will begin issuing phone numbers with the 424 code on July 17. Residents who establish service before that date could still be assigned a 310 number, provided the numbers have not run out.

Regulators had considered yet another split for 310, which would have foisted a new area code on the cities and communities of Carson, Catalina Island, Compton, El Segundo, Gardena, Hermosa Beach, Manhattan Beach, the Palos Verdes Peninsula, Redondo Beach, Torrance, as well as most of Hawthorne and a part of Inglewood.

But that was not a popular option, especially in Inglewood, which would have found its city chopped into three area codes. State regulators nixed the idea.

Despite the constant need for new codes nationally, few jurisdictions opt for the overlay instead of a split. For one, outlying regions are still fairly easily divided up.

And overlays tend to create a disincentive for phone customers to switch to rival carriers. For example, most customers wanting to switch to a competing phone company cannot keep their existing number. And because overlays assign a new area code to newly created numbers, a customer switching from, say, GTE to MediaOne might get a new area code as well as a new phone number.

For that reason and others, California regulators in 1996 banned the use of overlays in the state before 2001--but they made an exception for 310.

Other overlay codes exist in Atlanta, Chicago, Denver, New York City, as well as in Florida and Maryland. And they are gaining popularity.

In the meantime, California continues to split, with five new area codes emerging this year. Recent Southern California changes include:

* Area code 626, formally split off from the 818 region earlier this year. Affected areas include Alhambra, Altadena, Arcadia, Azusa, Covina, Duarte, El Monte, Glendora, Industry, Irwindale, La Puente, Monrovia, Monterey Park, San Gabriel, San Marino, Sierra Madre, South Pasadena, most of Pasadena and a small part of Glendale.

* Area code 323, introduced on June 13 as a split from the 213 area code. By Jan. 16, callers must use the new code to reach residents and businesses in a doughnut-shaped swath surrounding downtown Los Angeles. This includes Commerce, East Los Angeles, West Hollywood, Highland Park, Huntington Park, Hyde Park, Montebello, Monterey Park, South Gate and Watts. A three-mile diameter region of downtown Los Angeles keeps the 213 code.

* Area code 949. Splitting off from the 714 area code, the 949 code was introduced in parts of Orange County in April and will formally take effect Oct. 17.

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Times staff writer Elizabeth Douglass can be reached via e-mail at elizabeth.douglass@latimes.com.