The free minute did not work

The minute covers the first sixty seconds of connected time and the call continues afterwards, billed per second from your credit. With no credit, the call ends when the free minute is exhausted rather than continuing into a negative balance — which is the behaviour most people want, and it is worth knowing so the ending does not read as a dropped call.

Because billing is per second, a trial call of forty seconds uses forty seconds and leaves twenty. There is no rounding that swallows the remainder, and no expiry on what is left of it.

If the call ended at almost exactly a minute and you did have credit, that is not the trial running out — a call that ends near a round number repeatedly is usually a timer somewhere else, and dropped calls covers what those are.

A free minute is a demonstration rather than a promotion, and its job is narrow: to let you hear what a call actually sounds like to the number you care about, before any money changes hands. Call quality to one destination tells you very little about another, so the only useful test is the one you make yourself, to the person you actually call.

That is also why it needs no registration. Asking for an email address to unlock a trial converts a test into a transaction and gives us a list we do not want to hold; the app works without an account at all, which is one of the few genuinely unusual things about it — why Telvio works this way sets out the rest.

One per installation is the cost of it being unconditional. An offer with no identity attached has to be limited by something, and the installation is the least invasive thing available to limit it by.

It is worth using it deliberately rather than spending it on the first number to hand, because the thing it can tell you is narrow and the thing people assume it tells them is broad.

Call quality on an internet call is decided by the whole path: your connection, the route between our carrier and the destination country, and the network that finally delivers the call. None of that generalises. A flawless call to a landline in Germany tells you almost nothing about a mobile in Nigeria, because the two share only the first leg. So spend the minute on the number you actually intend to call, from the connection you will usually be on. That is the only test that answers the question you have.

It is also worth calling at a realistic hour. Congestion is real and it has a daily shape at both ends: a call at three in the morning local time is the easiest possible test and the least representative one. If you normally call in the evening, test in the evening.

What the minute cannot test is the price, because it is free. Check the rate the app shows before dialling against the published rates, and if the destination is one you will call often, work the cost out for a month rather than for a call — the arithmetic is short and it is the number that actually matters.