LWC Training Corp.
Voice over IP Online Course
Lesson 3 - How Does VoIP Work?
Voice over IP has parallels to the traditional public switched telephone network. Both systems
need to identify the end points of a telephone call and route conversations between them.
Both systems also need to be able to physically put the conversation on the wire, keep it
coherent as it travels across the system and be made understandable when it reaches the
destination. This chapter examines how these functions are accomplished by a voice over IP
A. Call control
B. Call manager
C. Transmitting voice
Review and Final Exercise
Upon completion of this section, students will:
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- Appreciate that making a telephone call requires two phases, setting up the call (call
control) and the actual transmission. VoIP requires these same two phases.
- Have been exposed to the control function of a telephone call and the functions that this
performs. In addition, the student will understand how the control function is implemented on
a PSTN using SS7 and on a Voice over IP network using H.323 or SIP.
- Understand the four steps that are required to put voice on an IP network: sampling,
quantizing, encoding and packetizing