SonicWALL 2.5 User Manual

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Chapter 28: 
Configuring VoIP Support
This chapter provides overview information and configuration tasks on enabling Voice over IP (VoIP) 
protocols. VoIP is a term used in IP telephony for a set of facilities for managing the delivery of voice 
information using IP. In general, this means sending voice information in digital form in discrete 
packets rather than in the traditional circuit protocols of the public switched telephone network 
(PSTN). A major advantage of VoIP and Internet telephony is that it avoids the tolls charged by 
traditional telephone service. 
Firewall > VoIP
The SonicWALL security appliance supports the most widely used VoIP standard protocols and the 
most commonly used VoIP vendors and systems on the market. Providing full VoIP support on the 
SonicWALL security appliance enables organizations with increasingly decentralized workforces to 
access corporate voice services from remote sites. VoIP systems consist of multiple clients (such as 
IP phones or soft phones) and VoIP servers residing at different parts of the network. 
VoIP Protocols
This section provides a concept overview on H.323 and SIP protocols. Refer to the “Configuring the 
VoIP Settings” section for configuration tasks for H.323 and SIP networks.
H.323 
H.323 is a comprehensive suite of protocols for voice, video, and data communications between 
computers, terminals, network devices, and network services. H.323 is designed to enable users to 
make point-to-point multimedia phone calls over connectionless packet-switching networks such as 
private IP networks and the Internet.
H.323 is widely supported by manufacturers of video conferencing equipment, VoIP equipment and 
Internet telephony software and devices.
An H.323 network consists of four different types of entities:
• Terminals - Client end points for multimedia communications. An example would be an H.323 
enabled Internet phone or PC
• Gateways - Connectivity between H.323 networks and other communications services, such as 
the circuit-switched Packet Switched Telephone Network (PSTN)