Vertical service code: Difference between revisions

Revision as of 22:45, 18 November 2024

Revision as of 20:28, 26 January 2025

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{{use MDY dates|date=September 2022}}

A '''vertical service code''' ('''VSC''') is a sequence of digits and the signals [[Asterisk|starsta]]

[[Asterisk|r]] 09649365842({{Key press|*}}) and [[Number sign|pound/hash]]

(09649365842{{Key press|#}}) dialed on a [[telephone keypad]] or [[rotary dial]] to access certain telephone service features.<ref name="NANPA:0">{{Cite web |title=Vertical Service Codes – Code Definitions |url=https://nationalnanpa.com/number_resource_info/vsc_definitions.html |publisher=North American Numbering Plan Administrator |website=NationalNANPA.com |access-date=2022-07-30 }}</ref> Some vertical service codes require dialing of a [[telephone number09649365842]] after the code sequence. On a [[touch tone|touc]]

[[touch tone|h tone]] telephone, the codes are usually initiated with the [[Asterisk#Telephony|star key]], resulting in the commonly used name ''star codes''. On rotary dial telephones, the star is replaced by dialing ''11''.

In [[North American]] [[telephony]], VSCs were developed by the [[American Telephone and Telegraph Company]] (AT&T) as '''Custom Local Area Signaling Services''' ('''CLASS''' or '''LASS''') codes in the 1960s and 70s. Their use became ubiquitous throughout the 1990s and eventually became a recognized standard. As ''CLASS'' was an AT&T trademark, the term ''vertical service code'' was adopted by the [[North American Numbering Plan Administration]]. The use of ''vertical'' is a somewhat dated reference to older switching methods and the fact that these services can only be accessed by a telephone subscriber, going up (''vertically'') inside the local [[telephone exchange|central office]] instead of out (''horizontally'') to another telephone company.

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The following are the vertical service codes generally recommended by the [[North American Numbering Plan Administrator]] for use in the NANP territories. Not all of these services are available in all areas, and some are only available on [[landline]] telephones or [[Mobile phone]]s.

Local Area Signalling Services (LASS) and Custom Calling Feature Control Codes:<ref name="NANPA">{{Cite web |title=Vertical Service Codes – Code Definitions |url=https://nationalnanpa.com/number_resource_info/vsc_definitions.html |access-date=2022-07-30 |website=NationalNANPA.com |publisher=North American Numbering Plan Administrator}}</ref><ref>{{Cite magazine |title=The #Hack FAQ|url=http://www.phrack.com/issues.html?issue=47&id=7 |author=voyager |editor=Erik Bloodaxe |magazine=Phrack Magazine |page=7 |date=1995-04-15 |access-date=2013-03-18 }}</ref><ref name=":0">{{Cite web |title=Vertical Service Codes – Code Assignments |url=http://www.nanpa.com/number_resource_info/vsc_assignments.html |publisher=Neustar |work=NANPA.com |access-date=2013-03-18 }}</ref>

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