CRBT, PRBT and RBT are the common terms used in Nepal to represent Ring Back tones for different telecom operators of Nepal. According to Wikipedia - Ring-Back Tone or Audible Tone is defined as
A ringback tone is an audible indication that is heard on the telephone line by the calling party after dialing and prior to the call being answered at the receiving end. It is normally a repeated tone, designed to assure the calling party that the called party's line is ringing, although the ring-back tone may be out of sync with the ringing signal.
- Nepal Telecom (CRBT)
- NCell (PRBT)
- UTL (RBT)
- Smart Telecom