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P2302RL-P1 Support Notes
must specify the service port and the LAN IP of this server in Menu 15. Thus SUA is able to forward the
incoming packets to the requested service behind SUA and the outside users access the server using the ZyXEL
Device's WAN IP address. So, we have to configure the internal IPsec as a default server (unspecified service
port) in menu 15 when it acts a server gateway.
VoIP FAQ
What is Voice over IP?
Voice over IP is an emerging technology based on open standards of IEEE, fundamentally the Internet Protocol,
that allows voice data to travel across the Internet. There are many method to used this technology, the most
common and well known are SIP, and H.323.
How does Voice over IP work?
Basically VoIP is a technic to send voice information in digital form in discrete packets over digital network
rather than by using traditional circuit switch (PSTN). To do so we will need an analog to digital converter on
sender side to translate the voice (analog signal) to digital than transmit it, and on the receiver end it will also
need an analog to digital converter to covert the digital signal back to analog to the person being called can
heard the voice.
Why use VoIP?
Traditionally telephony carrier use circuit switching for carrying voice traffic. As circuit switching is designed
to carry voice and it does it very well. Than why use IP for voice? As broadband booms, and technology
evolve. People now want to communicate through various way not just voice such as email, instant
messaging, video and so on. Traditional telephony can not evolve as quickly as the demand and develop new
feature on circuit switch takes much time and money. IP is an already exist standard and many type of service
already runs on IP, by using IP as a platform integrate service is now possible and low cost where traditional
circuit may take long time to achieve.
What is the relationship between codec and VoIP?
In order to transfer voice (analog signal) over IP it first need to be digitized. Codec is a technic to digitize
analog signal to digital and vice versa. There are various speech codec available and can be used with VoIP
each with it's advantage and disadvantage.
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All contents Copyright 2007 ZyXEL Communications Corporation.
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