当用户拨号上网后 ,电话线就被上网者较长时间占用 ,上网者无法再接听电话。 Phone Doubler系统向用户提供了一种使用一条电话线既可上网又可接听电话的服务。与此同时 ,Phone Doubler系统的使用也使目前 PSTN网络中用户忙率居高不下的状况得到改善。文中着重介绍了 Phone Doubler系统的功能及在 PSTN网络中的应用 ,并展望了 Phone Doubler系统的应用前景 When the user dials the Internet, the phone line is occupied by the Internet for a long time, the Internet can no longer answer the call. The Phone Doubler system offers users a service that uses both a phone line and an answering phone. In the meantime, the use of the Phone Doubler system has also improved the current high rates of users in the PSTN network. This article focuses on the introduction of the function of Phone Doubler system and its application in PSTN network and prospects of the application of Phone Doubler system