METHOD AND SYSTEM FOR REALIZING NONLOSS TRANSMISSION OF MEDIA STREAM AFTER SWITCHING BETWEEN OPEN CALL AND SECRET CALL

摘要

A method for implementing lossless transmission of a media stream after switching from a plain-call to a cipher-call, comprises the following steps: after a base station receives a plain-call to cipher-call switch message for switching from a plain-call to a cipher-call from a communication terminal, inserting a special media frame into the media stream and then sending the media stream to a media gateway; the media gateway determining whether to detect the special media frame or not according to incoming and outgoing media bearing modes or media encoding-decoding formats of the media stream, and the media gateway passing through the media stream from the incoming to the outgoing regardless of whether the special media frame is detected or not to be detected. When the special media frame is detected, the media stream is either directly passed through or adapted to 64kbps/56kbps PCM, depending on the encoding-decoding types.