A vertical service code (VSC) is a sequence of digits and the signals star (*) and pound/hash (#) dialed on a telephone keypad or rotary dial to access certain telephone service features.[1] Some vertical service codes require dialing of a telephone number after the code sequence. On a touch tone telephone, the codes are usually initiated with the 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 central office instead of out (horizontally) to another telephone company.

Feature definitions

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 phones.

Local Area Signalling Services (LASS) and Custom Calling Feature Control Codes:[1][2][3]

Vertical service codeService definitionAustraliaJapanUK
Tone
dialing		Pulse
dialing
  • 51
1151Who called me. Provides the directory number, date and time of unanswered calls.
  • 52
1152Call Hold (Single Line Variety Package). Permits the call to be picked up at another station.
  • 53
1153Distinctive Ring B. Allows a subscriber to alert a specific party distinctively.
  • 54
1154Distinctive Ring C. Allows a subscriber to alert a specific party distinctively.
  • 57
1157Call trace (Malicious caller identification)
  • 60
1160Call blocking
  • 61
1161Priority call
  • 62
1162Selective call waiting
  • 63
1163Selective call forwarding
  • 65
1165Calling number delivery activation
  • 66
1166Continuous redial
  • 67
1167Calling number delivery blocking1831
#31#[4][5]		141
#31#[6]
  • 68
1168Activate call forwarding on busy
  • 69
1169Last-call return (incoming)1361
1363[9]		1471[10]
  • 70
1170Call waiting disable
  • 71
1171Usage sensitive three-way call
  • 72
1172Unconditional forward: All calls
  • 73
1173Call forward: Cancel
  • 74
1174Speed calling (8 numbers)
  • 75
1175Speed calling (30 numbers)
  • 77
1177Anonymous call rejection activation
  • 78
1178Do not disturb
  • 79
1179Do not disturb disable
  • 80
1180Call blocking disable
  • 81
1181Priority call disable
  • 82
1182Caller ID (per call)1470
  • 83
1183Selective call forwarding disable
  • 85
1185Caller ID disable
  • 86
1186Continuous redial cancel
  • 87
1187Anonymous call rejection deactivation
  • 88
1188Deactivate call forwarding on busy
  • 89
1189Last-call return cancel
  • 90
1190Conditional forward: Busy line
  • 92
1192Conditional forward: No answer
  • 94
1194Directed call pickup
  • 272
Wireless Priority Service

See also

References

  1. ^ "Vertical Service Codes – Code Definitions". NationalNANPA.com. North American Numbering Plan Administrator. Retrieved 2022-07-30.
  2. ^ voyager (1995-04-15). "The #Hack FAQ". Phrack Magazine. Erik Bloodaxe (ed.). p. 7. Archived from the original on April 5, 2013. Retrieved 2013-03-18.
  3. ^ "Vertical Service Codes – Code Assignments". NANPA.com. Neustar. Archived from the original on December 4, 2015. Retrieved 2013-03-18.
  4. ^ 1831 on landlines, or #31# from a mobile
  5. ^ "HOW TO: block your number when calling someone". Telstra Exchange. Telstra. Retrieved 28 May 2017.
  6. ^ 141 on landlines and #31# on mobiles
  7. ^ *10# for Telstra services "Telstra Home Phones and Plans – Call Return" Archived March 14, 2011 at the Wayback Machine
  8. ^ *69 on Optus HFC Telephony network. "Optus Personal – Using Call Return" This only allows one to return the last unanswered call, and can cost 35 cents per use.
  9. ^ 1361 to get number, 1363 to call back. "NewsRelease". NTT East. Retrieved June 20, 2013. "Number OSIRASE 136". NTT West. Retrieved June 20, 2013.
  10. ^ After dialing 1471, the caller can press "3" to automatically return the call. Previously free, since August 2004 the return call service incurs a charge.
  11. ^ 1832 on landlines, or *31# from a mobile