Voice over Internet Protocol (VoIP) network equipment, such as SIP phones, Terminal Adapters, and Media Gateways, converts voice signals into Internet Protocol (IP) packets for transport over the VoIP networks. These devices all use jitter buffers to store voice packets for some period of time before they are played back to the users, to avoid packet loss problems due to jitter, i.e., variations in packet delay, in the VoIP networks. Many of these devices use adaptive jitter buffers which vary the size of their jitter buffer in response to variations of the jitter in the network. There are many specialized algorithms that are used by adaptive jitter buffers which attempt to vary the buffer size to simultaneously minimize packet loss and delay on VoIP calls. Thus, adaptive jitter buffers increase or decrease the number of VoIP packets being stored in response to the amount of jitter in the VoIP network. However, each time the jitter buffer changes its size, a discontinuity, which causes voice quality impairments, is introduced in the voice signal. Thus, impairments caused by changes in the size of the jitter buffer include adding gaps of silence when a jitter buffer expands and deleting portions of voice signals when the jitter buffer shrinks. As such, network equipment having inferior algorithms for varying the size of their jitter buffer will cause noticeable impairments that will impact the quality of the voice signal.
USPTO Backgrounds
USPTO Backgrounds