TABLE OF CONTENTS
Setting
the standard
The
foundation: TCP/IP
Signaling
protocols
Speech
transmission protocols
Standard
bodies and forums
Additional resources
The rapid evolution of VoIP was made possible in part by the use of protocols
and standards, or special sets of rules that end points in a telecommunication connection use when
they communicate. Standard bodies are responsible for writing the rules that keep the lines of
communication wide open. The goals of standards organizations are centered primarily on developing,
amending, revising and updating standards to foster the ubiquity of a technology. In the case of
VoIP, vendors, architects and developers, researchers, telecom providers, and users rely on their
comprehensive expertise and experience to bring about successful and secure VoIP adoptions. See
below for list of standard bodies and forums.
TCP/IP
(Transmission Control Protocol/Internet Protocol) is the basic communication language or protocol
of the Internet. It can also be used as a communications protocol in a private network (either an
intranet or an extranet). When you are set up with direct access to the Internet, your computer is
provided with a copy of the TCP/IP program just as every other computer that you may send messages
to or get information from also has a copy of TCP/IP. Two protocols are also necessary for VoIP
service: a signaling protocol and a speech transmission protocol. Read on for a more detailed
explanation of TCP/IP.
Call signaling is used in Voice over IP (VoIP ) systems to establish connections between
endpoints, or between an endpoint and a gatekeeper. The most commonly used VoIP signaling protocols
are as follows:
SIP
(Session Initiation Protocol)
H.323
MGCP
(Media Gateway Control Protocol)
MEGACO (a
contraction of Media Gateway Controller) or H.248
SS7
(Signaling System 7)
ISDN
(Integrated Services Digital Network)
Q
signaling
UDP
(User datagram protocol)
RTP
(Real-Time Transport Protocol)
TCP
(Transmission Control Protocol)
DHCP
(Dynamic Host Configuration Protocol)
ENUM
RSVP
(Resource Reservation Protocol)
BGP (Border
Gateway Control)
COPS (Common
Open Policy Service Protocol)
CableLabs
ETSI (European Telecommunications Standards Institute)
H.323 Forum
IDPR.com (Internet Protocol Detail Record)
IETF (Internet Engineering Task Force)
IMTC (International Multimedia Telecommunications
Consortium)
IPTEL.org
ITU (International Telecommunications
Union)
MFA Forum
MSF (Multiservice Forum)
OpenH323
SIP Center
SIP Forum
W3C (World Wide Web Consortium)
Learning
guide: SIP
In this learning guide, you'll find out what SIP is, how it works, which applications are SIP
friendly, what compatibility and interoperability issues surround SIP and more.
Editor's
picks: Standards and protocols
Without standards and protocols, having a telephone conversation over the Internet or a dedicated
Internet Protocol (IP) network instead of dedicated voice transmission lines would not be possible.
In this collection of editor-selected resources, you'll find articles, news, expert advice,
webcasts, white papers and more covering H.323, SIP and the inherent challenges of
interoperability.
SIP school:
A to Z on SIP
In this complete guide to SIP, you'll learn how this signaling protocol's modularity and openness
simplifies communications, improves productivity and sets the stage for multimedia networks. School
is in session!
What are
media gateways and how do H.323, SIP, MGCP and other support protocols work?
Securing
SIP
In this complete guide to SIP, you'll learn how this signaling protocol's modularity and openness
simplifies communications, improves productivity and sets the stage for multimedia networks. School
is in session!
SIP and
the Future of VoIP - Expert Webcast
Gartner predicts that 90 percent of all new corporate telephone networks will be IP-enabled and
based on SIP protocols by 2008. It's only a matter of time before VoIP becomes a mission critical
communication system. Still, concerns remain around the security of VoIP and the underlying SIP
protocol, fearing that they are susceptible to similar types of threats and exploits that plague
the Web and email. In part one of this three-part Webcast, Andrew Graydon, Chair of the Security
Requirements Committee, VoIPSA, identifies the security issues associated with SIP and what you can
do to mitigate them.
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VoIP's call quality
and reliability has steadily improved, and now rivals the quality and dependability of traditional
TDM
(time-division multiplexing) calls while also offering users unprecedented mobility, call features
and services and marked cost savings.