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C
H A P T E R
This chapter shows how to configure the Voice over IP (VoIP) features on your system.
18.1 VoIP Overview
This section introduces VoIP, and discusses SIP and H.248 VoIP networks.
18.1.1 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 VOP 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.
18.1.2 SIP and H.248
The IES uses a VoIP line card for VoIP communications. This line card may use either SIP (see
Section 18.1.3 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.
18.1.3 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.
MSC1000G/1024G/1224G Series User's Guide
539) or H.248 (see
Section 18.1.4 on page
18
VoIP
543), depending upon the
539
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