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Practical guide

Wi‑Fi calling explained simply

"Wi‑Fi calling", "IP telephony", "VoIP": these words are everywhere, often for different things. This guide explains what really happens when you call over Wi‑Fi, why a call is sometimes perfect and sometimes choppy, how much data it uses and what to know about 9-1-1.

Guides · Reviewed · 5 min read

Two ways to call over Wi‑Fi

The first is a feature of your mobile carrier, often called "Wi‑Fi Calling" in the phone's settings. When the cellular signal is weak, for example in a basement or at a cottage, the phone sends your ordinary calls and texts over Wi‑Fi. It is your usual mobile number, billed under your mobile plan; you install nothing.

The second goes through an internet phone app. The app has its own number, or sometimes only a handle, and it works over Wi‑Fi or mobile data alike, on a phone, a tablet or a computer. That is how a virtual number or an internet business phone system works. Both approaches use the same basic technology, voice over IP, but they don't depend on the same provider and don't follow the same billing rules.

What happens during a call

Your voice is picked up by the microphone, turned into data by a codec, cut into small packets, then sent over the internet dozens of times per second. On the other side, the packets are put back in order and turned back into sound. If packets arrive late or get lost, the app has to guess what is missing: that is what causes a robotic voice, dropouts or a slight echo.

For voice, download speed matters less than people think. A call needs little bandwidth, but it needs a stable connection: little delay, little variation in that delay and little loss. A very fast but busy connection, for example during a big download or a high-definition video on another device, can give a worse call than a modest but quiet connection.

How much data a call uses

An internet voice call usually uses less than 1 MB per minute, depending on the codec and the quality the app chooses. An hour of calls is therefore a few dozen megabytes, much less than a video. Over Wi‑Fi at home, it is negligible. Over mobile data, it is reasonable, but check your plan if you call a lot on the go. Video calls use much more.

Improving your call quality

  1. Move closer to the router or add an access point: a concrete wall or a floor can weaken the signal a lot.
  2. If your router has two bands, the 5 GHz band is often less crowded but reaches less far than 2.4 GHz. Try both.
  3. Avoid big downloads and high-definition video on the same network during an important call.
  4. Restart the modem and router from time to time, and keep their software up to date.
  5. On public Wi‑Fi, wait until you are fully connected: some networks require you to accept terms on a web page before calls can go through.
  6. Use earphones with a microphone: they reduce echo and background noise.
  7. Keep the app and the phone's system up to date, and let the app send notifications, otherwise incoming calls may not ring.

Moving from Wi‑Fi to mobile data

When you leave home in the middle of a conversation, the phone switches from Wi‑Fi to mobile data. Depending on the app and the phone, the call may continue, pause briefly or drop. If an important call starts at home and has to continue in the car, it is better to start it on mobile data, or to call back once you are out. On the other hand, turn off Wi‑Fi if your phone clings to a weak network whose signal is worse than your mobile data.

Travelling

Abroad, a call through an app over the hotel Wi‑Fi can save you roaming charges to reach Canada. Conditions vary from one service to another: check what your plan includes and whether calls to Canada count as local calls. For your carrier's Wi‑Fi Calling feature, the billing rules abroad are your carrier's: ask before you leave. Either way, turn off data roaming if you want to be sure to use Wi‑Fi only.

9-1-1 and Wi‑Fi calls

This is the most important point. A 9-1-1 call over the internet does not always let emergency services locate you automatically. With your carrier's Wi‑Fi Calling, the carrier usually asks you to register an emergency address. With an internet phone app, the Canadian Radio-television and Telecommunications Commission (CRTC) requires the provider to tell you about 9-1-1 limits and ask for the address where you use the service. Keep that address up to date, and know that with no internet or no power, the call will not go through. Read our guide to 9-1-1 and internet phone service for details.

Who oversees what

Wi‑Fi uses radio frequency bands managed by Innovation, Science and Economic Development Canada (ISED), which also certifies radio devices sold in Canada, such as routers and phones. Phone services are overseen by the CRTC, in particular for 9-1-1 and number portability. If you have an unresolved problem with a phone provider, the Commission for Complaints for Telecom-television Services (CCTS) can help.

With MIMT

MIMT is an internet phone app: your Canadian number works over Wi‑Fi or mobile data, on your mobile and in your browser at app.mimt.ca. You keep your mobile plan and its Wi‑Fi Calling feature; MIMT adds to it. Before your first call to a phone number, the app asks for your 9-1-1 address. See the web app and the 9-1-1 limits.