Internet Protocol

1. IP Internetwork
• IP is connectionless.
• IP provides multiple paths from source to
destination.

2. Major VoIP Protocols

3. VoIP Protocols and the OSI Model

4. Bandwidth Implications of Codec

5. Impact of Voice Samples

6. Picture

7. IP address to Phone Number
• VoIP look for IP address
• Translate Phone numbers to IP addresses
• The central call processor is a piece of hardware running a specialized
database/mapping program called a soft switch.
• Soft switches know:
• Where the endpoint is on the network
• What phone number is associated with that endpoint
• The current IP address assigned to that endpoint
• If soft switch does not have the information, the request is handled by another
soft switch.

8. Protocols
• Used to connect different pieces of hardware.
• H.323
• Most widely used protocol
• provides specifications for real-time, interactive videoconferencing, data
sharing and audio applications (VoIP)
• SIP
• More streamlined protocol
• Developed specifically for VoIP
• Lack of a standard protocol is a problem. Not always compatible.

9. Advantages
• Cost
• Free VoIP to VoIP
• Low cost VoIP to Public Switch Telephone Network (PSTN)
• Less bandwidth requirements
• Low cost / no cost software and hardware
• Mobility
• Any internet connection
• Growing number of wireless broadband locations

10. VoIP Architectures
• PC to PC
Internet

11. VoIP Architectures
• Phone to Phone via the Internet
Internet

12. VoIP Architectures
• Phone to Internet to Gateway to PSTN
Internet
GATEWAY
PSTN

13. Cisco 7970 IP Phone

14. IP hard phones

15. VoIP phone interface

16. Media gateway
• An active device for interfacing PSTN lines to
VoIP server.
• Available in 8, 16 and 24 port denominations
• Converts analog signals to digital and vice versa
• H.323 protocol used between VoIP server and
media gateway for call handling

17. Codec
 Acronym for coder-decoder
 Separate codec used for audio and video
 One of the function is to compress the raw audio /
video to save bandwidth
 Efficiency of codec determines the quality of audio
/ video
 Popular audio codecs G711, G722, G723, G726,
G729
 Popular video codecs H261, H263, H264

18. Schematic of a VoIP setup

19. Signal flow in VoIP

20. How a VoIP phone is connected
 Do not need additional data and power point
 Single data point serve both PC & Phone
 POE (Power Over Ethernet) provide power for
VoIP phone
VoIP
POE enabled

21. Integrated TIFR voice communication system