A ringback tone is an audible indication that is heard on the telephone line by the caller while the phone they called is still in use. It is normally a repeated tone, designed to assure the calling party that the called party’s line is ringing.
Ringback tone(接通回音)指电话处于正常使用状态时，打电话的人从听筒中听到的声音提示。这种声音一般都是一个重复的音调，目的只是提示打电话的人，对方的电话正在接通中。
Ringback music, also called personalized ringback tone, is a piece of music heard by the caller instead of the traditional telephone ring signal when a telephone call is placed.
Ringback music(“个性化接通回音”)则是打电话时，传统的电话提示音被音乐所取代，于是成为了我们所说的“彩铃”。