The present invention relates to a method of managing a trunk, and querying and ascertaining a ring-back sound to provide the ring-back sound in a subscriber-based ring-back sound service. In the trunk management method, a terminating mobile switching center (32) requests the intelligent peripheral (50) to release a trunk call when the terminating mobile switching center recognizes the answer of the terminating subscriber or when a first predetermined period of time has elapsed from a time when it is recognized that a corresponding ring-back sound is provided to the originator. Further, the intelligent peripheral (50) requests the terminating mobile switching center (32) to release the trunk call when a second predetermined period of time has elapsed from a time when the ring-back sound is provided.