An Introduction About Voice Over Internet Protocol (VoIP)

 

Internet Protocol Voice over Internet (VoIP)

Training and and Development

 

IP Telephony Telephony Model Public Switched Telephone Network Initially, PC to PC Initially, voice calls over the Internet

Gateways allow PCs to also reach phones

PSTN Gateway

Multimedia PC

IP Network Gateway Multimedia PC

PSTN

…or phones to reach

phones

 

Why VoIP ?  Allows

voice to be an IP Application

 Converged

Networks

Voice, Video & Data over an IP network  Monetary

Savings

 

 

Functional Elements

In IP-Telephony networks, following functional elements are

mostly found.

 Media Gatew Gateway ay

•

 Media Gateway Controller

•

•

 Signaling Gateway

 

Media Gatew Gateway ay Media Gateway performs functions like  like 

• Physical T1/E1 facility termination • Voice Packe Packetization tization • Voice Compression using ITU recommendations G.711,G.723.1 and G.729 etc

 

Media Gateway Controller (MGC) • A media gateway controller is the overall controller of the system. • Media Gateways receives commands from the media gateway controller which define their operations. MGC performs core functions like:

• Address Resolution • Call Routing • Resource Management • Call Detail Record (CDR) Generation

A media gateway controller controller is also a lso known as a Soft Switch

 

Signaling Gateway (SG) gateway ay transfers signaling information between • Signaling gatew

PSTN node and Media gatewa gateway y controller (MGC)

 

Media Gateway Media Gateway Controller Signaling Gateway

May be separate physical devices or Integrated in any combination e.g. SG/MG functions Implemented Implement ed in one unit

 

IP Telephony Telephony Model

SS7

PSTN

PSTN

MGC

Node

PSTN Trunks

SG

SG

MG

RTP / UDP / IP

IP Network

SS7

Node

MG PSTN Trunks