VoIP Gateway
VoIP gateway hardware and software
is required to make the translation between VoIP and
PSTN networks. Obtaining a VoIP gateway is necessary
in order to join and translate hybrid telephony networks
seamlessly. A VoIP gateway converts TDM traffic from
the Public Switched Telephone Network (PSTN) into either
H.323 or Session Initiation Protocol (SIP)-based VoIP
traffic. Considered intelligent endpoints, the gateways
can provide billing, alarming, built-in interactive
voice response (IVR), routing, digit manipulation, and
security.
A VoIP gateway may also be known
as a Media Gateway, SoftSwitch, Media Gateway Controller,
SIP Server, or other device that handles VoIP data and
signalling traffic. A gateway is a network point that
acts as an entrance to another network. On the Internet,
a node or stopping point can be either a gateway node
or a host (end-point) node. Both the computers of Internet
users and the computers that serve pages to users are
host nodes. The computers that control traffic within
your company's network or at your local Internet service
provider (ISP) are gateway nodes.
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The
primary functions of a VoIP gateway include voice,
video and fax compression and decompression, packetization,
call routing, and control signaling. Additional
features may include interfaces to external controllers,
such as Gatekeepers or Softswitches, billing systems,
and network management systems. Some VoIP gateways
are built as dual router / gateways. A VoIP router
serves to forward data packets from one network
to another.
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A VoIP gatekeeper (not to be
confused with gateway) is an optional feature for a
VoIP network. A gatekeeper is useful for routing and
central management of all endpoints in a given zone.
This includes the management of terminals, gateways
and MCU's (multipoint control units). The gatekeeper
provides logic variables for proxies or gateways in
a call path to provide connectivity with the Public
Switched Telephone Network (PSTN), to improve Quality
Of Service (QoS), and to enforce security policies.
A VoIP gatekeeper provides address translation, bandwidth
control, and access control to a network of VoIP terminals
and gateways. The network of all elements (gateways,
gatekeepers, VoIP terminals) under control of a gatekeeper
is defined as an H.323 Zone.
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| Security
is a great concern for any VoIP gateway. Since a VoIP
gateway is another piece of Internet equipment, like a
server or a PC with an Internet connection, it can be
a target of a hacker attack. Denial of Service (DoS) attacks
can be especially critical to a VoIP gateway along with
intrusion, monitoring and alteration of data packets.
Identity theft and SPIT (Spam Over Internet Telephony)
also are major concerns. The major goals for securing
any VoIP gateway are authorization, authentication, integrity,
privacy and non-repudiation. Achieving these goals requires
configuration, authentication, key exchange and encryption.
It is imperative that all of these security concerns be
address for VoIP to grow and prosper inside the consumer
market as well as the business world.
Just as Internet security has
evolved on servers client PC's, it will also evolve
on gateways as well. This is not a stopping point for
VoIP, just another hurdle that will have to continually
updated and maintained as it is now with any other Internet
device. The VoIP gateway is not only a gateway between
Internet telephony and the traditional PSTN phone companies,
but a bridge between now and the future of all telephony
as well.
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