Vertical service code
 | The examples and perspective in this article deal primarily with the United States and do not represent a worldwide view of the subject. (December 2019) |
A vertical service code (VSC) is a sequence of digits and the signals star (*) and number sign (#) dialed on a telephone keypad or rotary dial to enable or disable 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 AT&T Corp. 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 local telephone subscriber, going up (vertically) inside the local central office instead of out (horizontally) to another telephone company.
Feature definitions[]
North America[]
The following are the vertical service codes generally recommended by the North American Numbering Plan Administration for use in the NANP territories. Not all of these services are available in all areas, and some are only available to landline or cellular telephones.
Local Area Signalling Services (LASS) and Custom Calling Feature Control Codes:[2][1][3]
| Vertical service code | Service definition | |
|---|---|---|
| Tone dialing |
Pulse dialing | |
| *51 | 1151 | Who called me. Provides the directory number, date and time of unanswered calls |
| *52 | 1152 | Call Hold (Single Line Variety Package). Permits the call to be picked up at another station. |
| *53 | 1153 | Distinctive Ring B. Allows a subscriber to alert a specific party distinctively. |
| *54 | 1154 | Distinctive Ring C. Allows a subscriber to alert a specific party distinctively. |
| *57 | 1157 | Call trace |
| *60 | 1160 | Call blocking |
| *61 | 1161 | Priority call |
| *62 | 1162 | Selective call waiting |
| *63 | 1163 | Selective call forwarding |
| *65 | 1165 | Calling number delivery activation |
| *66 | 1166 | Continuous redial |
| *67 | 1167 | Calling number delivery blocking |
| *68 | 1168 | Activate call forwarding on busy |
| *69 | 1169 | Last-call return (incoming) |
| *70 | 1170 | Call waiting disable |
| *71 | 1171 | Usage sensitive three-way call |
| *72 | 1172 | Unconditional forward: All calls |
| *73 | 1173 | Call forward: Cancel |
| *74 | 1174 | Speed calling (8 numbers) |
| *75 | 1175 | Speed calling (30 numbers) |
| *77 | 1177 | Anonymous call rejection activation |
| *78 | 1178 | Do not disturb |
| *79 | 1179 | Do not disturb disable |
| *80 | 1180 | Call blocking disable |
| *81 | 1181 | Priority call disable |
| *82 | 1182 | Caller ID (per call) |
| *83 | 1183 | Selective call forwarding disable |
| *85 | 1185 | Caller ID disable |
| *86 | 1186 | Continuous redial cancel |
| *87 | 1187 | Anonymous call rejection deactivation |
| *88 | 1188 | Deactivate call forwarding on busy |
| *89 | 1189 | Last-call return cancel |
| *90 | 1190 | Conditional forward: Busy line |
| *92 | 1192 | Conditional forward: No answer |
| *94 | 1194 | Directed call pickup |
| *272 | Wireless Priority Service | |
See also[]
- Mobile dial code
- Pat Fleet – Prompt voice for most U.S. AT&T implementations of VSC features
- Public switched telephone network
- Short code
- Signalling System 7
Telephones portal
References[]
- ^ a b "Vertical Service Codes – Code Definitions". NANPA.com. Neustar. Retrieved 2013-03-18.
- ^ voyager (1995-04-15). Erik Bloodaxe (ed.). "The #hack FAQ". Phrack Magazine. p. 7. Retrieved 2013-03-18.
- ^ "Vertical Service Codes – Code Assignments". NANPA.com. Neustar. Retrieved 2013-03-18.
This article incorporates public domain material from the General Services Administration document: "Federal Standard 1037C".
- Calling features
- North American Numbering Plan
- Telephone numbers in Canada
- Telephone numbers in the United States
- Telephone numbers