Free tools for people who make calls

Telvio is an app for placing ordinary phone calls over an internet connection. Almost every support message we get about call quality turns out not to be about the network at all: it is a headset the operating system has not selected, an input level so low that noise suppression eats the speech, or a browser that is holding onto a device another program grabbed first. None of that is specific to us. It is the same set of problems that makes somebody unhearable on Zoom, on Teams, on a job interview and on a call to their family.

So the tools here are the checks we would ask you to run before we looked at anything on our side. They run entirely in your browser. Nothing is uploaded, nothing is stored, and none of them needs an account. The microphone tests use the browser's own audio pipeline, the number and rate tools use a lookup table that ships with the page, and the time planner uses your device's clock and time-zone database.

They are also, frankly, how a small site earns its first readers. Somebody searching for zoom mic test has an immediate problem and thirty seconds to solve it. Solving it properly is a better introduction than an advertisement.

The four microphone tests share one engine and differ in what surrounds it. The engine asks the browser for your microphone, measures the signal as RMS loudness on a decibel scale, draws it as a moving meter, and gives a verdict: silent, quiet, comfortable, or clipping. It then records six seconds and hands the audio back so you can hear what you sound like, which catches the problems a meter cannot — a fan, a hard echo, a headset boom pointed at your cheek instead of your mouth.

The application-specific pages add what the meter cannot tell you: where the relevant setting lives in Zoom, in Google Meet and in Microsoft Teams, what each of those applications does to your audio before it leaves your machine, and which of their defaults most often produce the complaint you are trying to fix.

The phone number validator answers a narrower question than most tools of its name. It tells you which country a number belongs to, whether its length is plausible under that country's numbering plan, and whether its leading digits sit in a range that country assigns to mobiles or to landlines. It does not tell you the line is in service — nothing that runs in a browser can — and it says so rather than showing a green tick you would be wrong to trust.

The cost calculator prices a call at our published rate and, next to it, prices the same call the way a provider that bills in whole minutes would. That second number is the one nobody publishes, and on a short call it is often twenty to thirty per cent higher for exactly the same conversation.

The planner draws your day and the other person's day as two 24-hour strips with the callable overlap highlighted. It reads today's offset from your browser's time-zone database, so it is right during daylight saving transitions, when a fixed offset written into an article is wrong for weeks.

This is worth being precise about, because a page asking for microphone access has earned the question.

The microphone tests call the browser's getUserMedia API, connect the resulting stream to an analyser node for the meter, and — only when you press record — to a recorder whose output becomes a temporary object in the page's own memory. There is no upload, no server, and no audio processing anywhere but on your machine. Closing the tab discards everything; navigating away releases the device.

The number validator and the cost calculator work from a lookup table that is part of the page you already downloaded. Neither sends the number or the country you typed anywhere. The planner reads your time zone from the browser and does arithmetic locally.

The site does run Microsoft Clarity for anonymous usage analytics, which records page interactions, and that is disclosed in the privacy policy. It does not have access to your microphone or to anything you type into these tools.

A green meter proves the microphone reaches the browser. It does not prove the audio reaches the person you are calling, and the gap between those two is where the remaining problems live.

The most common one is that a second application has the device. On Windows and on macOS, an application that has claimed a microphone in exclusive mode can leave every other application with silence, and the browser will still show your headset in its device list. Quitting the other application — the conferencing client you left running, the recording software, the virtual audio router — is the fix, and it is worth doing before anything more elaborate.

The second is that the conferencing application is using a different device from the browser. They keep separate settings. A browser test tells you the headset works; it tells you nothing about which input Teams selected when you plugged it in mid-meeting.

The third is upstream. If your voice arrives broken up rather than absent, the problem is bandwidth or packet loss, not the microphone, and no microphone setting will fix it. Move closer to the access point, switch off other devices that are streaming, or use a wired connection.

For calls placed with Telvio specifically, the app needs a working data connection but not a fast one: a voice call uses roughly 30 to 40 kilobits per second in each direction. What it does not tolerate well is a connection that drops packets in bursts, which is what a congested hotel or airport network usually does.