A Multimedia Customized Ring Back Tone (MRBT) service platform, a terminal and a system for implementing an MRBT service are provided in the present invention. A method for implementing an MRBT service is further disclosed, which includes: performing, by a Multimedia Ring Back Tone (MRBT) platform, a first media capability negotiation with a calling party before a called party answers a call after the calling party initiates the call to the called party; playing, by the MRBT platform, an MRBT for the calling party according to the result of the first media capability negotiation. The scheme of the present invention may implement an MRBT service in a 3G communication network.