Voip - ZyXEL Communications MSC1000G User Manual

This chapter shows how to configure the Voice over IP (VoIP) features on your system.
16.1 VoIP Overview
This section introduces VoIP, and discusses SIP and H.248 VoIP networks.
16.1.1 Introduction to VoIP
VoIP (Voice over IP) is the sending of voice signals over the Internet Protocol. This allows you to
make phone calls and send faxes over the Internet at a fraction of the cost of using the traditional
circuit-switched telephone network. You can also use servers to run telephone service applications
like PBX services and voice mail. Internet Telephony Service Provider (ITSP) companies provide
VoIP service.
Circuit-switched telephone networks require 64 kilobits per second (kbps) in each direction to
handle a telephone call. VoIP can use advanced voice coding techniques with compression to reduce
the required bandwidth.
The VoIP port connects POTS (Plain Old Telephone System) end-user telephone subscribers to the
IP network by converting the analog voice signal into data packets and transmitting them over the
network.
16.1.2 SIP and H.248
The IES uses a VoIP line card for VoIP communications. This line card may use either SIP (see
Section 16.1.3 on page
firmware version it is currently using. You can use the same hardware with either firmware version.
See your VoIP line card's User's Guide for more information.
16.1.3 Introduction to SIP
The Session Initiation Protocol (SIP) is an application-layer control (signaling) protocol that handles
the setting up, altering and tearing down of voice and multimedia sessions over the Internet.
SIP signaling is separate from the media for which it handles sessions. The media that is exchanged
during the session can use a different path from that of the signaling. SIP handles telephone calls
and can interface with traditional circuit-switched telephone networks.
Management Switch Card User's Guide
C
HAPTER
599) or H.248 (see Section 16.1.4 on page
1 6

VoIP

603), depending upon the
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