Have you ever seen a phone like the one in the photo? There are no buttons, just a wheel with holes in it. How do you think people called someone on it? And how is that different from a WhatsApp call today?
Image source: File:Model 500 landline phone.jpg (Wikimedia Commons)
In this post:
- How a traditional landline works
- What VoIP is and what you need to use it
- The benefits and drawbacks of each
- Two sorting and matching activities, a comparison task and a quiz
The traditional landline
A landline is a telephone connected by a cable to the telephone company’s network. For over a hundred years, this network used copper wires that carried your voice as an electrical signal to a telephone exchange, which connected you to the person you called.
- It stays in one place: at home, at school or in an office.
- You pay a monthly rental for the line, and often extra for long-distance and overseas calls.
- Call quality is usually clear and steady.
- You can always call emergency numbers such as 999 (police) or 990 (fire) in Trinidad and Tobago.
- Some older phones work during a power cut, because the line itself powers them. Newer cordless phones need electricity.
VoIP: calling over the Internet
VoIP stands for Voice over Internet Protocol. Your voice is turned into digital data, chopped into small packets and sent over the Internet, like any other data. When you make a WhatsApp call, a video call on FaceTime, Zoom, Google Meet or Microsoft Teams, or a Viber call, you are using VoIP. (Skype, one of the first popular VoIP apps, was closed by Microsoft in 2025.)
What you need for a VoIP call
| You need… | Why |
|---|---|
| A device: smartphone, tablet or computer | To run the app |
| An Internet connection (Wi-Fi or mobile data) | To carry the call; a faster connection means a clearer call |
| A microphone | So the other person can hear you |
| Speakers or headphones | So you can hear them |
| The same app on both ends (and an account) | A WhatsApp user can call another WhatsApp user, but not a Zoom user |
| A camera (for video calls) | So they can see you |
Phones and laptops have the microphone, speaker and camera built in. Many businesses also use special VoIP desk phones that plug into the office network instead of a phone line.
Image source: File:VoIP telephone.svg (Wikimedia Commons)
VoIP vs landline
| VoIP | Landline | |
|---|---|---|
| How the call travels | As data over the Internet | Over the telephone company’s lines |
| Where you can use it | Anywhere with Internet | Only where the phone is plugged in |
| Cost of overseas calls | Free or very cheap (just data) | Can be expensive per minute |
| Video and group calls | Yes | No (voice only) |
| Extras | Messages, file sharing, screen sharing during calls | Few |
| Needs Internet and power? | Yes. A slow connection makes calls choppy or laggy. | No Internet needed |
| Emergency calls | Most apps cannot call 999 or 990 | Yes |
Watch: what is VoIP?
This animated video explains what VoIP is and how it works. It is about 7½ minutes long, so you might watch it in two parts.
Video: What is VoIP? – PowerCert Animated Videos – https://www.youtube.com/watch?v=n_b2sJP2pBk
Activity: VoIP, landline or both?
Try it: sort the features
Drag or tap each card into the right box.
VoIP
Landline
Both
Activity: what do you need?
Try it: VoIP requirements
Match each job to the thing that does it.
| Lets the other person hear you | |
| Lets you hear the other person | |
| Carries the call as data | |
| Lets the other person see you | |
| Lets you find and call your friend |
Compare it yourself
With a parent’s permission, make one WhatsApp (or other app) call and one landline or ordinary mobile call. Copy and complete this table:
| Question | App (VoIP) call | Landline call |
|---|---|---|
| What did you need to make the call? | ||
| How clear was the sound? | ||
| Could you see each other? | ||
| Roughly what did it cost? | ||
| Which would you use to call family overseas? Why? |
Self-check quiz
Click the best answer. You get feedback straight away; only your first click counts towards your score.
1. VoIP stands for…
2. Which of these is a VoIP call?
3. Which is NOT needed for a VoIP call?
4. What usually happens to a VoIP call on a very slow connection?
5. A big advantage of VoIP is…
6. A big advantage of a landline is…
Related posts on islandclass.org
Next: Working Together Online: Wikis and Google Drive
Syllabus link: Forms 1–3 ICT curriculum, Module 4, Objective 4.8 – distinguish between communication using VoIP and traditional land line.
Attributions to media used in this post:
- Model 500 landline phone.jpg – Crcjfly – CC BY-SA 4.0 (via Wikimedia Commons)
- VoIP telephone.svg – mark.starikov – CC0 (via Wikimedia Commons)
- Video: What is VoIP? – PowerCert Animated Videos (YouTube)
Updates
2026/10/21
– Fixed the activity code so its buttons keep working.
© 2026 Vedesh Kungebeharry. All rights reserved.