Patent ID: 8213341

Claim:
A communication method that gives permission of participation to a receiving apparatus intending to participate in a group by performing follow-up participation in a group call communication being performed among a plurality of numbers belonging to a predetermined group, wherein at a transmission end, the method comprising: a step of encoding and framing an inputted voice signal to generate voice frames of voice data; a step of discriminating which of sonant audio or silent audio the inputted voice signal is when starting a group call and of incorporating a group number needed for the group call communication into a voice frame which is discriminated to be silent audio; a step of composing at least a predetermined number N of continuous voice frames and a flag of identifying whether all the N continuous voice frames are sonant audio or at least any one of the N continuous voice frames is not sonant audio, to form a transmission frame; a step of wirelessly transmitting the transmission frame, at a reception step performing the follow-up participation to a group, the method comprising: a step of receiving the wirelessly transmitted signal to decode it to a transmission frame; a step of decoding a voice frame in the decoded transmission frame; a first judgment step of judging from the flag in the decoded transmission frame whether all the N voice frames are sonant audio or at least any one of the N voice frames is not sonant audio; a step of outputting voice data in the decoded voice frame if all the N voice frames are judged to be sonant audio in the first judgment step; a second judgment step of judging whether data in the decoded voice frame is valid or invalid as voice data if at least any one of the N voice frames is judged to be sonant audio in the first judgment step; a third step of outputting the data in the decoded voice frame as voice data if it is judged to be valid as voice data in the second judgment step and of judging whether the data in the decoded voice frame is valid or invalid as a group number if it is judged to be invalid as voice data in the second judgment step; a step of performing error handling if it is judged to be invalid as a group number in the third step; a step of performing a protocol process based on the group number if it is judged to be valid as a group number; a step of allowing a group call to be received, converting the voice data to a voice signal and canceling a mute to emit sound if the group number is judged to coincide with a group number of a group to which itself belongs, in the protocol process; and a step of not canceling the mute if the group number is judged not to coincide with a group of a group to which itself belongs, in the protocol process.