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.
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 code | Service definition | Australia | Japan | UK | |
|---|---|---|---|---|---|
| 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 (Malicious caller identification) | |||
| *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 | 1831 #31# [4] [5] | 141 #31# [6] | |
| *68 | 1168 | Activate call forwarding on busy | |||
| *69 | 1169 | Last-call return (incoming) | *69 HFC *10# [7] [8] | 1361 1363 [9] | 1471 [10] |
| *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) | *31#/1832 [11] | 1470 | |
| *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 | ||||
This article incorporates public domain material from Federal Standard 1037C. General Services Administration. Archived from the original on January 22, 2022.
