Area codes 909 and 840 are telephone

area code A telephone numbering plan is a type of numbering scheme used in telecommunication to assign telephone numbers to subscriber telephones or other telephony endpoints. Telephone numbers are the addresses of participants in a telephone network, rea ...

s in the

North American Numbering Plan The North American Numbering Plan (NANP) is an integrated telephone numbering plan for twenty-five regions in twenty countries, primarily in North America and the Caribbean. This group is historically known as World Zone 1, World Numbering Zone ...

for the far-eastern part of

Los Angeles County Los Angeles County, officially the County of Los Angeles and sometimes abbreviated as LA County, is the most populous county in the United States, with 9,663,345 residents estimated in 2023. Its population is greater than that of 40 individua ...

, southwestern

San Bernardino County San Bernardino County ( ), officially the County of San Bernardino and sometimes abbreviated as S.B. County, is a county located in the southern portion of the U.S. state of California, and is located within the Inland Empire area. As of th ...

, and a small portion of Riverside County in the U.S. state of

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

. Area code 909 was created on November 14, 1992, in an area code split of 909, and 840 was added to the numbering plan area to form an

overlay complex In telecommunications, an area code overlay complex is a telephone numbering plan that assigns multiple area codes to the same geographic numbering plan area (NPA). Area code overlays are implemented in territories of the North American Numbe ...

effective February 23, 2021. While most of western Riverside County now uses Area code 951, some residents in Eastvale and Corona were allowed to keep the 909 area code after the split in 2004.

History

In 1947, when the

American Telephone and Telegraph Company AT&T Corporation, an abbreviation for its former name, the American Telephone and Telegraph Company, was an American telecommunications company that provided voice, video, data, and Internet telecommunications and professional services to busi ...

(AT&T) devised the first nationwide

telephone numbering plan A telephone numbering plan is a type of numbering scheme used in telecommunication to assign telephone numbers to subscriber telephones or other telephony endpoints. Telephone numbers are the addresses of participants in a telephone network, reach ...

and assigned the original North American area codes, the state of California was divided into three numbering plan areas: 213, 415, and 916, for the southern, central, and northern parts of the state, respectively. The area served by 213 extended from Mexican border to the Central Coast. Starting in the 1950s, Southern California experienced rapid expansion of telephone service, requiring area code 213 to be split five times by 1998. The first split became necessary in 1951, when most of the southern and eastern portion, including

San Diego San Diego ( , ) is a city on the Pacific coast of Southern California, adjacent to the Mexico–United States border. With a population of over 1.4 million, it is the List of United States cities by population, eighth-most populous city in t ...

and most of Orange County, was assigned area code 714. On November 14, 1992, the numbering plan area 714 in southern California was divided in an area code split to form an additional numbering plan area, assigned the area code 909. After an initial permissive dialing period, dialing of the area code became mandatory in August 1993. On August 26, 1999, the NANPA approved a request by the California Public Utilities Commission for a two-phase split/overlay plan to provide area code relief for 909. In the initial phase, nearly all of western Riverside County was to be split off from 909 into area code 951 on September 9, 2000. Meanwhile, preparation for phase two was to have begun on February 12, 2000, with 1+10-digit permissive dialing being introduced for the remainder of 909 in advance of a new 752 overlay NPA with an in-service date set for February 10, 2001. Because of the nationwide outcry and protests at the time regarding the large number of area code splits as well as outrage over the requirement of 10-digit dialing in regions now served by recently introduced overlay area codes, the CPUC decided they would mitigate consumers' complaints by implementing a series of two-phase "split/overlay" relief actions so that an "equal amount of inconvenience" would be experienced by each group: those who were losing their area code would get to keep seven-digit dialing for calls within their new area code, while the rest got to keep their original area code but would be required to dial 1+10 digits for all calls, be they local or long distance. However, with the implementation of 1,000-block

number pooling Telephone number pooling, thousands-block number pooling, or just number pooling, is a method of allocating telephony numbering space of the North American Numbering Plan in the United States. The method allocates telephone numbers in blocks of 1,0 ...

, both portions of the 909 split/overlay were cancelled before either phase could be implemented. (Similar plans were being considered to provide relief to the 310, 415, 510, 760 and 818 area codes as well; however, due to number rationing, all were postponed indefinitely and later permanently cancelled.) Nevertheless, even with numbering conservation measures in place, the NANPA determined in 2003 that 909 would indeed require relief. As had been originally planned in September of 2000, western Riverside County was split off from 909 and assigned area code 951 on July 17, 2004. 909 continued to serve small portions of Corona, Riverside, Moreno Valley, and the entire city of Calimesa, all of which are in Riverside County, as well as small portions of eastern Los Angeles and northern Orange Counties; area code 752 was returned to the numbering pool to be reassigned at a later date. On July 23, 2019, the California Public Utilities Commission approved an all-services overlay for area code 909 with the new area code 840, effective February 23, 2021. A permissive dialing period was implemented from July 2020 to January 2021. While 840 numbers are issued to new subscribers, those with 909 numbers retain them.

Service area

Los Angeles County

* Claremont * Diamond Bar * Glendora (mostly in the 626 area code) * City of Industry (mostly in the 626 area code and small portion in the 562 area code) * La Verne * Pomona * Rowland Heights (also in the 626 area code and small portion in the 562 area code) * San Dimas *

Walnut A walnut is the edible seed of any tree of the genus '' Juglans'' (family Juglandaceae), particularly the Persian or English walnut, '' Juglans regia''. They are accessory fruit because the outer covering of the fruit is technically an i ...

(small portion in the 626 area code) * West Covina (mostly in the 626 area code)

Riverside County

* Calimesa * Corona (mostly in the 951 area code) * Eastvale (mostly in the 951 area code)

San Bernardino County

* Big Bear City *

Big Bear Lake Big Bear Lake is a reservoir in the Western United States, western United States, located in the San Bernardino Mountains in San Bernardino County, California, San Bernardino County, California. It is a snow and rain-fed lake, having no other m ...

* Bloomington * Blue Jay * Chino Hills (small portion in the 657/714 area code) * Chino * Colton (small portion in the 951 area code) * Crestline * Fontana * Grand Terrace (small portion in the 951 area code) *

Highland Highlands or uplands are areas of high elevation such as a mountainous region, elevated mountainous plateau or high hills. Generally, ''upland'' refers to a range of hills, typically from up to , while ''highland'' is usually reserved for range ...

* Lake Arrowhead * Loma Linda * Lytle Creek * Mentone * Montclair * Muscoy *

Ontario Ontario is the southernmost Provinces and territories of Canada, province of Canada. Located in Central Canada, Ontario is the Population of Canada by province and territory, country's most populous province. As of the 2021 Canadian census, it ...

* Rancho Cucamonga * Redlands * Rialto * Running Springs * San Antonio Heights * San Bernardino *

Sugarloaf A sugarloaf was the usual form in which refined sugar was produced and sold until the late 19th century, when granulated and cube sugars were introduced. A tall cone with a rounded top was the end product of a process in which dark molasses, ...

* Upland * Yucaipa

References

External links

North American Numbering Plan Administrator
(NANPA) {{coord, 34.1, -117.5, region:US-CA_type:adm2nd_dim:50km, display=title 909 San Bernardino County, California Riverside County, California Inland Empire Pomona Valley San Bernardino, California Telecommunications-related introductions in 1992 909