VoIP, or Voice over Internet Protocol, is a technology that allows users to make voice calls using an Internet connection instead of a regular phone line. It works by converting voice signals into digital data packets that travel over the Internet and are then reconstructed at the other end. There are several VoIP protocols used and many applications that employ VoIP, including Skype. VoIP offers advantages over traditional phone service like lower costs, additional features included for free, and the ability to make calls from any Internet-connected device.

2. What is VoIP? VoIP [Voice over Internet Protocol] is family of communication protocols and transmission technique which is used in delivery of voice communication or multimedia sessions over internet.

3. How VoIP works? VoIP protocols first converts your voice or media into digital signal and travels over the internet. At receiver side it decode in its original format. VoIP allows you to make a call from your desktops/laptops or from IP phones using internet. You can make a call from your traditional telephones using spceial type of phone adapter.

4. How VoIP works?

5. VoIP Protocols Some VoIP protocols : H.323

6. IMS [IP Multimedia System]

7. MGCP [Media Gateway Control Protocol]

8. SIP [Session Initiation Protocol]

9. RTP [Real-time Transport protocol]

10. SDP [Session Description Protocol]

11. IAX [Inter-Asterisk eXchange]

12. What is PSTN? PSTN [Public Switched Telephone Network] is the network of circuit-switched telephone network which is based on telephone lines, fibre optics, celluler networks, communication satelites etc. It is our conventional method of voice communication which is based on circuit switching which are now replaced by VoIP technique.

13. PSTN vs. VoIP Carrier Lines PSTN : Dedicated lines required from telecom company

14. VoIP : Only an internet connection is required Bandwidth PSTN : Each telephone lines require 64kbps in each direction

15. VoIP : Using compression, VoIP can use only 10kbps in each direction Features PSTN : call waiting, call conference, caller ID available at an extra cost

16. VoIP : all features are generally free

17. Continue . . . Upgrade and Expansion PSTN : Very complex due to change in hardware and wires

18. VoIP : Sometimes just require more bandwidth and software uprade Rental PSTN : Expensive compare to VoIP

19. VoIP : About 1/4 times less expensive to PSTN Remote PABX extension PSTN : Very costly and require each dedicated line for each

20. VoIP : It is a standard feature of VoIP

21. Applications Some application that you used in your daily life is based on VoIP. Like Skype, Gtalk, Yahoo Messenger, Fring, E-buddy, Nimbuzz, Twinkle, Brosix, SIPSet, Gizmo, iChat, iCall that are used on various platform like Windows, Linux, MAC OS X, Android and many mobile platforms.

22. Some Application

23. VoIP Devices [1] ATA : Most useful device for VoIP is ATA (Analog telephone Adaptor). It helps you to connect your standard phone to computer and lets you call.

24. Continue… [2] Computer-to-computer : Its the easiest way to make VoIP calls. You just need to have a software, microphone, speaker and sound card (and internet connection obviously ! ! !).There are not any additional charges for this.