Telephony quality of service

Encyclopedia : T : TE : TEL : Telephony quality of service

In the fields of telephony, the engineering term Quality of Service (QoS) comprises all the aspects of a connection, such as time to provide service, voice quality, echo, loss, reliability and so on. A subset of telephony QoS is Grade of Service (GOS), which comprises aspects of a connection relating to the capacity of a network.ITU-T Study Group 2, Teletraffic Engineering Handbook (350 pages, 2.7 MB)(It uses abbreviation GoS instead of GOS) http://www.com.dtu.dk/teletraffic/handbook/telenook.pdf

In circuit-switched networks, GOS is the probability of one party not being able to initiate a call to another party, that is, a call attempt blocked and lost owing to congestion.

For a discussion on QoS in a cellular mobile telephone network, see the page on Mobile QoS.

What is telephony quality of service?

When looking at circuit-switched networks, QoS is affected by various factors, which can be divided into "human" and "technical" factors. Human factors include: stability of service, availability of service, delays, user information. Technical factors include: reliability, scalability, effectiveness, maintainability, Grade of Service, etc.Peuhkuri M., IP Quality of Service, Helsinki University of Technology, Laboratory of Telecommunications Technology, 1999.

Why is telephony GOS monitoring needed?

In circuit-switched networks, the GOS expresses the blocking experienced owing to congestion and can result in calls being lost. Thus it is the responsibility of the telecommunications service provider to monitor and manage the GOS of all its services to ensure that the GOS is maintained for every origin and destination pair.

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