The invention discloses a telephone service quality test method. The method comprises the following steps: initiating a video call according to number information of a tested terminal by simulation; instructing a media gateway to establish an end point which communicates with the tested terminal; instructing the media gateway to perform video communication with the tested terminal by the end pointafter encoding and decoding negotiation of the media gateway with the tested terminal so as to test video telephone quality of the tested terminal. The telephone service quality test method is characterized by function-enhanced mobile switching center and media gateway, the mobile switching center initiates a simulation video call, the media gateway performs encoding and decoding multiplexing andde-multiplexing and the encoding and decoding negotiation to realize the simulation video call and video call test in a 3G network. The invention also discloses a mobile switching center and a telephone service quality test system.