Patent ID: 7738361

Claim:
A method for generating fill frames for Voice over Internet Protocol (VoIP) applications in a communication device, comprising: determining if there is a lost frame in a received communication, wherein if it is determined that there is a lost frame, setting a frame loss flag and storing the frame loss flag in the frame loss history register; shifting a loss history register, a line spectral frequency (LSF) history register, a voicing cutoff (VCUT) history register, a pitch history register, and a root mean squared (RMS) gain history register, wherein the loss history register, the LSF history register, the VCUT history register, the pitch history register, and the RMS history register include at least three registers, the three registers being a newest, a middle and an oldest registers; reading the frame loss flag into a newest loss history register; determining contents of the middle register of each of the LSF history register, the VCUT history register, the pitch history register, and the RMS history register according to a state of the frame loss history register, wherein the frame loss history state is represented by a three digit binary number, the three digits representing a frame loss state of a previous three frames, a value of “0” indicating a lost frame, a value of “1” indicating a received frame, with a symbol “X” indicating one of a received frame and a lost frame, the value of which does not bear on the middle register contents, and wherein an average of the previous and future frame values are used if the frame loss history state is 101, the value of the previous frame is used if the frame loss history state is 001, and the value of the future frame is used if the frame loss history state is 100; and sending the contents of the middle registers to a synthesizer to generate an output speech signal.