Table of Contents
Advertisement
Prestige 2302RL Support Notes
Why use VoIP?
Traditionally voice data is transmitted using circuit switching. Since circuit switching is designed to carry
voice, it does it very well. However, as broadband networks become a mainstream for network access and
technologies have evolved, we don't want to confine ourselves to just using text-based applications (such as
e-mail, instant messaging, etc.) for communication over the Internet. Thus, the convenience of voice
communication through the Internet has quickly become popular.
In addition, it would take a much longer time, more effort and money to implement new
features using circuit switching. Since the IP technology is a standard and various
applications are available, it is easier and more cost-effective to integrate new services
and applications using IP.
What is the relationship between codec and VoIP?
In order to send voice (analog signal) over IP, it first needs to be digitized. Codec is a technique used to digitize
analog signal into digital signals and vice versa. There are various speech codec available for VoIP. Each codec
has its advantages and disadvantages.
What advantage does Voice over IP provide?
VoIP provides advanced integration of text, video and voice in emails. This cannot be done using traditional
circuit switching (PSTN).
What is the difference between H.323 and SIP?
H.323 and SIP are proposed by different groups. Session Initiation Protocol (SIP) is a standard introduced by
the Internet Engineering Task Force in 1999 to carry voice over IP. Since it was created by the IETF, it
approaches voice and multimedia from the Internet, or IP. Whereas H.323 emerged around 1996, and as an
International Telecommunication Union standard, it was designed from a telecommunications perspective. Both
standards have the same objective - to enable voice and multimedia convergence with IP protocols.
Can H.323 and SIP interoperate with each other?
In interoperability between the two, the industry is making slow but sure progress. Interoperability must first
happen between vendor implementations of the same protocol (SIP-to-SIP and H.323-to-H.323) and then
between protocols. Currently in order for SIP client to talk to H.323 client the ITSP must have a trunking
gateway act as a translator between the two protocols without the truncking gateway the two protocols are not
able to communicate to one another.
140
All contents copyright (c) 2007 ZyXEL Communications Corporation.
Advertisement
Table of Contents
