Implementing a High Quality VOIP Device

摘要

A method is provided for Voice over Internet Protocol (VoIP) devices to communicate over an Internet Protocol (IP) network. The method includes synchronizing the VoIP devices using one or more dual-tone multi-frequency (DTMF) codes over a telephone network, retransmissions of voice packets in bursts, retransmissions of voice packets following a time lag, adjusting the number of retransmissions based on quality of service, retransmission of a missing voice packet identified in a list received from a peer device, discarding low energy voice frames in a jitter buffer to prevent overflow, stopping playout at a low energy voice frame when the jitter buffer is below a minimum buffer size, and selective transmission and retransmission of voice packets based on their energy levels.

主权项

1: A method for a first Voice over Internet Protocol (VoIP) device to communicate with a second VoIP device over an Internet Protocol (IP) network, comprising:
communicating at least one dual-tone multi-frequency (DTMF) code with the second VoIP device over a telephone network to synchronize time between the first and the second VoIP devices; recording a local time at the first VoIP device when the first and the second VoIP devices are synchronized by said communicating as a first synchronization base time; keeping a first synchronization time comprising the local time at the first VoIP device minus the first synchronization base time; transmitting a first voice packet to the second VoIP device over the IP network, the first voice packet including the first synchronization time when the first voice packet was transmitted; receiving a second voice packet from the second VoIP device over the IP network, the second voice packet including a second synchronization time when the second voice packet was transmitted from the second VoIP device, the second synchronization time comprising a local time at the second VoIP device minus a second synchronization base time at the second VoIP device, the second synchronization base time comprising the local time at the second VoIP device when the first and the second VoIP devices are synchronized from said communicating; and determining a network delay as a difference between the first and the second synchronization times.