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Glossary of VOIP Terms - Page 4 |
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M3UA - M3UA is the MTP3 User Adaptation Layer protocol that adapts SS7 MTP3 messages for transport over an IP network
using the SCTP protocol. This is a very recent protocol adopted in September 2000. This protocol is aware of SS7
point codes and circuits. It translates point codes into IP addresses for SS7 message transport across the IP network. |
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Media Gateway - A media gateway is an IETF and MGCP concept. It is a device that converts one form of media into another form, for
example, PSTN voice into VoIP, and has very little intelligence. |
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Media Gateway Controller - A media gateway is an IETF and MGCP protocol concept. It is a device that controls one or more media gateways and
has enough intelligence to be able to control nearly all aspects of each media gateway, but does not have enough
intelligence to control an entire call. |
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Megaco - Megaco is the IETF name for the ITU-T H.248 protocol standard recommendation for controlling a media gateway
when connecting telephone calls between a LAN and the PSTN. It handles many telephony issues such as redundant
MGC systems that MGCP does not address. This recommendation was announced in August 2000. The Megaco
protocol is similar to the MGCP protocol but is not backward-compatible with it, meaning a system using Megaco will
not interoperate with a system using MGCP |
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MGCP - Media Gateway Control Protocol is a protocol designed to control various devices that can handle different types of
media, e.g., voice, video, data, etc. It is designed to allow a Media Gateway Controller (MGC) to control one or more
unintelligent Media Gateway (MG) devices. |
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MTP2 - MTP2 is the Message Transfer Part [layer] 2 protocol that transmits and guarantees receipt of a SS7 message between
two adjacent systems in the SS7 data network using the traditional SS7 A-links or F-links. |
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MTP3 - MTP3 is the Message Transfer Part [layer] 3 protocol that routes SS7 messages given to it over the SS7 data network.
It is aware of SS7 point codes and how to route messages to them. When it has selected a route to a particular point
code, it uses the MTP2 protocol to transmit the message to the next system in the SS7 data network. |
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Packet-switched - A technique for routing data through a network by encapsulating the data in packets, labeling them with addresses and
routing information (the packet header), and then routing the packets over various physical circuits (oftentimes
different for each packet) until they reach their intended destination. Packets from the same source are not considered
related to each other and thus each packet must make its own way through the network. A packet may not reach its
intended destination due to network congestion and can be discarded. This network characteristic cannot guarantee
quality of service, the lack of which the public IP network known as the Internet is famous. |
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PBX - A Private Branch Exchange is a very small, specialized switch similar to a CO switch. It permits the attached
telephones to call each other using shorter numbers, and requires the caller to select an “outside line” in order to call
through the PSTN. |
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PCM - Pulse Code Modulation is the name of the G.711 voice codec algorithm that is used to convert analog voice into digital
data. It converts analog voice into 8,000 8-bit data samples every second. It has two implementations; A-law used
throughout most of the world and mu-law used throughout North America and Japan. |
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POTS - Plain Old Telephone Service is the term applied to the normal telephone service delivered by a PSTN CO switch. |
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PRI - Primary Rate Interface. This term is always used in connection with ISDN, as in “ISDN PRI”. It refers to a digital
circuit, such as a T1 or E1, that carries multiple calls and uses the ISDN signaling protocol. |
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PSTN - The Public Switched Telephone Network is the public, wire-line, switched network based on TDM circuits and used to
transport PCM-encoded voice calls. It is often times referred to as the SCN, or Switched Circuit Network, by those in
the packet-switched data network world. |
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PTT - The PTT network is a term used to refer to the PSTN network of other countries. It comes from the abbreviation for
Post, Telephone and Telegraph, which used to be the government-owned company within other countries that owned
and managed the national postal, telephone and telegraph systems. |
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Router - A router is a hardware and software system that directs data packets entering the router toward their intended
destinations. Routers have various physical interfaces such as 100baseT Ethernet, T1, E1, DS3, OC-3, etc. Routing is
based upon the destination address contained within the header of the IP data packet. |
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RTCP - The Real-time Transport Control Protocol is used to report on the performance of a particular RTP transport session. It
delivers information such as the number of packets transmitted and received, the round-trip delay, jitter delay, etc. that
are used to measure Quality of Service in the IP network. |
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RTP - The Real-time Transport Protocol is a protocol that is used to transport real-time data, such as voice or video. This is
an “unreliable” protocol built on top of the UDP protocol that does not guarantee delivery of packets, but which has
little overhead.
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