used to manage the delivery of voice information over the
Internet.VoIP involves sending voice information in digital form in
discrete packets rather than by using the traditional
circuit-committed protocols of the public switched telephone network
(PSTN). A major advantage of VoIP and Internet telephony is that it
avoids the tolls charged by ordinary telephone service.
Ask questions about VoIP at ITKnowledgeExchange.com
VoIP derives from the VoIP Forum, an effort by major equipment
providers, including Cisco, VocalTec, 3Com, and Netspeak to promote
the use of ITU-T H.323, the standard for sending voice (audio) and
video using IP on the public Internet and within an intranet. The
Forum also promotes the user of directory service standards so that
users can locate other users and the use of touch-tone signals for
automatic call distribution and voice mail.
In addition to IP, VoIP uses the real-time protocol (RTP) to help
ensure that packets get delivered in a timely way. Using public
networks, it is currently difficult to guarantee Quality of Service
(QoS). Better service is possible with private networks managed by an
enterprise or by an Internet telephony service provider (ITSP).
A technique used by at least one equipment manufacturer, Adir
Technologies (formerly Netspeak), to help ensure faster packet
delivery is to use ping to contact all possible network gateway
computers that have access to the public network and choose the
fastest path before establishing a Transmission Control Protocol (TCP)
sockets connection with the other end.
Using VoIP, an enterprise positions a "VoIP device" at a gateway. The
gateway receives packetized voice transmissions from users within the
company and then routes them to other parts of its intranet (local
area or wide area network) or, using a T-carrier system or E-carrier
interface, sends them over the public switched telephone network.
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