supplementary service

基本解释

Supplementary service: law firm, language training school, preparatory college, overseas school, employment agency.
配套服務：律師事務所、語言培訓學校、預科學校、海外學院、就業機搆等。
The Sub-addressing (SUB) supplementary service allows the called (served) user to expand his addressing capacity beyond the one given by the ISDN number.
子尋址（SUB）補充業務允許被叫（被服務）用戶在給定的ISDN號碼基礎上擴展其尋址容量。
www.ptsn.net.cn
Because there's an essential signaling difference between IP phone and traditional voice service, IP phone supplementary service is developed based on special protocols.
由於IP電話系統在信令結搆方麪與傳統電話系統的集中模型有本質的區別，因此基於IP電話系統附加業務的開發和控制協議具有不同的特點。

The Unstructured Supplementary Service Data (USSD) code (which we won't reproduce here) apparently only works on Samsung phones running Touchwiz, and only if you are directed to the dodgy destination while inside the stock browser (rather than Chrome, for example).
ENGADGET: 'Dirty USSD' code could automatically wipe your Samsung TouchWiz device (updated)