Latency Problems

VoIP service delay or latency is characterized as the amount of time it takes for speech to exit the speaker’s mouth and reach the listener’s ear. Latency sounds like an echo. There are 3 types of delay commonly found in today’s VoIP networks:

1. Propagation Delay: Light travels through a vacuum at a speed of 186,000 miles per second, and electrons travel through copper or fiber at approximately 125, 000 miles per second. A fiber network stretching halfway around the world (13,000 miles) induces a one-way delay of about 70 milliseconds (70 ms). Although this delay is almost imperceptible to the human ear, propagation delays in conjunction with handling delays can cause noticeable speech degradation.
2. Handling Delay: Devices that forward the frame through the network cause handling delay. Handling delays can impact traditional phone networks, but these delays are a larger issue in packetized environments.
3. Queuing Delay: When packets are held in a queue because of congestion on an outbound interface, the result is queuing delay. Queuing delay occurs when more packets are sent out than the interface can handle at a given interval.

The solution to this VoIP service problem would be to prioritize. Prioritizing VoIP traffic over the network yields latency and jitter improvements. Policy based network management, bandwidth reservation, Type of Service, Class of Service, and Multi-Protocol Label Switching (MPLS) are all widely used techniques for prioritizing VoIP traffic. A quality VoIP router can solve many of these issues and will result in business quality VoIP service.