Transcript VOIP - PTCL Training & Development

Voice over Internet Protocol
(VoIP)
Training and Development
IP Telephony Model
Public Switched
Telephone Network
Initially, PC to PC
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 Gateway
• Media Gateway Controller
• Signaling Gateway
Media Gateway
Media Gateway performs functions like
• Physical T1/E1 facility termination
• Voice Packetization
• 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 is also known as a Soft Switch
Signaling Gateway (SG)
• Signaling gateway transfers signaling information between
PSTN node and Media gateway 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 in one unit
IP Telephony Model
SS7
SG
PSTN
Node
PSTN
Trunks
SG
PSTN
Node
MGC
MG
RTP / UDP / IP
IP Network
SS7
MG
PSTN
Trunks