A VoIP System is often associated with bandwidth savings and reduced cost. However, since this is a relatively new technology, there are many quality related issues to be dealt with. Many of these issues arise owing to the use of packet switched networks.

A significant problem that is associated with a VoIP system is the delay in packet transmission. This delay results in echo and talk overlaps. An echo is usually caused if the round trip delay of the signal from the destination back to the source is more than 50 milliseconds. In packet switched network, given the number of routers and networks a voice packet has to traverse, the delay can be considerable for long distance calls. Modern VoIP systems therefore implement echo control and cancellations methods to deal with the problem. Another problem caused with packet delays is talk overlaps. This problem occurs if the packet delay in any direction exceeds 250 milliseconds.

Apart from delays, another problem associated with VoIP networks is jitter. Jitter is caused by the inter-packet delay in the network. This causes distortion in the talks. Jitters can be minimized by holding the packets until the slowest packets arrive at the destination. This can however increase the delay in playing the voice. Various approaches are being tried at to compromise between delays and jitters.

Another severe problem affecting a packet network is packet losses. IP networks usually have high incidences of packet loss as compared to ATM networks. During peak traffics, the problem of packet losses can be enormous. Data packets can be retransmitted, but in case of voice packets a different approach is required. Some of the solutions proposed for solving this problem include replaying the last packets until new packets arrive, sending redundant information to compensate for the loss, and a hybrid approach combining the previous two methods.

This article is written for AccessDirect, providers of Unified Messaging, Voice Mail, and VoIP PBX Phone systems. Visit us at www.messagingservice.com

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AccessDirect, providers of Unified Messaging, Auto Attendant, Voice Mail, Fax Mail,and Virtual/Hosted PBX Phone systems with local and toll free numbers.