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Computer Networks · Class 12 · Network Protocols · Calls and Remote Login
networksprotocols⏱️ 6 min read

VoIP

🎬 This chapter has a 10:53 video: Network Protocols →

A WhatsApp call to a cousin abroad costs nothing extra, while an international phone call used to cost a lot a minute. The difference is the road the voice takes: the Internet instead of the telephone network.

1What VoIP is

VoIP
VoIP stands for Voice over Internet Protocol. It lets us make voice calls (and video calls) over the Internet, instead of through the regular telephone network. It is also called Internet telephony.

VoIP works on a simple idea: the analog voice signal is converted into digital data, cut into packets, and sent over the Internet. At the other end the packets are turned back into sound.

A call made of packets

Play the call on a good connection, then on a slow one. Drag sideways to turn.

Press ▶ Play to make a VoIP call from Delhi to Ambala.

A teaching model: one packet per word, with fixed delays. A real call sends about fifty small packets every second.

2Advantages and disadvantage

✅ Advantages
  • Free or very cheap, even for international calls.
  • Calls can be made and received anywhere with Internet access.
  • The same connection carries video, so it is used for video conferencing too.
❌ Disadvantage
  • Call quality depends on the Internet speed. A slow connection makes the voice break up, as in the lab.
The case-study clue
When a case study says video conferencing, online meetings, live interaction or voice communication over the Internet between two offices, the protocol it wants is VoIP.

3From the board papers

1
Fill in the blank: ______ is a communication methodology designed to deliver both voice and multimedia communications over Internet protocol. (a) VoIP (b) SMTP (c) PPP (d) HTTPCBSE sample paper 2022-23
1 mark
▶Show the answer

(a) VoIP.

2
Which of the following options is the correct protocol used for phone calls over the internet? (A) PPP (B) FTP (C) HTTP (D) VoIPCBSE board exam 2025
1 mark
▶Show the answer

(D) VoIP.

3
The students will be attending a lot of online academic sessions and workshops. These will involve audio-visual communication. Write the full name of the protocol which will be used for such a communication through the internet.CBSE board exam 2026 (case study)
1 mark
▶Show the answer

Voice over Internet Protocol (VoIP).

4
What is the use of VoIP?CBSE sample paper 2025-26 (case study)
1 mark
▶Show the answer

VoIP (Voice over Internet Protocol) allows users to make phone calls and other communications over the Internet instead of a traditional phone line. — CBSE’s marking scheme answer.

4Check yourself

Quick Check

A VoIP call keeps breaking up. What is the most likely cause?

Quick Check

Before a voice can be sent with VoIP, what happens to it?

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