Every app wants your phone number now. Here is why

A few years ago, a phone number was something you gave to a delivery driver or a bank. Today it is requested by food apps, clothing shops, newsletter sign-ups, streaming services and the form for a free trial of almost anything. Sometimes it is optional, often it is "strongly recommended", and increasingly it is required before you can see a price.

The number feels harmless. It is not secret, and you hand it out all the time. But a phone number is not a contact detail any more. It is a key that opens other doors, and that is exactly why so many services want a copy.

Reason one: proving you are a real person

The most defensible reason is fraud prevention. A new account tied to a working phone number is harder to create in bulk than one tied only to an email address, because phone numbers cost something to obtain. Sending a one-time code by text message lets a service check that a human with a real phone is on the other end.

This is a legitimate concern, especially for services that give away free trials, credits or discounts that bots would happily exploit. The trade-off is that you are now sharing something more permanent than an email address, which you can create and discard easily.

Reason two: signing you in and recovering the account

Many services use a text message as a second sign-in step or as the way back into an account when a password is lost. It is convenient: everyone has a phone, and no app needs to be installed.

The weakness is that a phone number is controlled by your mobile carrier, not by you. Talk a carrier into transferring the number to a new SIM, and whoever holds that SIM gets every code. That attack, known as SIM swapping, is the reason security people prefer authenticator apps over text messages. It is also why we require an authenticator app for every LegitVCC account rather than codes by SMS; our help center explains how the app-based code works.

Reason three: matching you across services

This is the commercial reason, and it is rarely stated on the form. Email addresses change; people have several of them. Phone numbers tend to stay with a person for years. That makes a number an excellent identifier for connecting your account at one company with data about you held elsewhere, including advertising platforms that match customer lists against their own users.

When a shop asks for your number "to send order updates", it may also be building a profile that follows you after the order is delivered.

Reason four: a direct marketing channel

A text message is opened more reliably than an email, and a phone number allows contact through messaging apps as well. For a marketing team, a list of verified phone numbers is valuable. Some sign-up forms bundle consent to marketing messages with the request for your number, or make the opt-out easy to miss.

Reason five: it reduces friction for the seller

A phone number also makes repeat purchases easier for the seller. Some checkouts use it as a quick way to recognize returning customers and pre-fill saved details. That can be convenient for you too, but it means the number becomes a partial password: knowing it, plus a code, may unlock your saved addresses and payment methods.

We have written before about how prices that appear late shape a decision, in drip pricing. Data requests work in a similar way. The number is often requested after you have invested time in a basket, when refusing feels like starting over.

What a number says on its own

Even without any other data, a phone number carries information. The country code reveals where the line was issued. In many places the prefix hints at the carrier, and some lookup services can tell whether a number is a mobile line, a landline or a virtual number from an internet service. Fraud teams use exactly these clues to decide how much to trust a new account.

Combined with a name, a number becomes a strong way to recognize you across services, and it can surface in data broker listings that link it to past addresses. That is not a reason for panic. It is a reason to treat the number as something closer to an identity document than a casual contact detail.

When giving it makes sense

There are good reasons to hand over a number:

• a delivery that genuinely needs a contact for the courier;
• a bank or payment service that uses it for fraud alerts;
• a service where you have chosen text messages as one factor among others, knowing the risks.

In each case, the number serves a purpose you understand.

When to think twice

Be more cautious when:

• the number is required just to see prices or browse;
• the form does not say what the number will be used for;
• marketing consent is pre-selected or bundled with the request;
• the service offers no alternative to text-message codes for security.

Practical options

You have more choices than "give it" or "leave":

1. Skip optional fields. Many forms mark the number as required visually but accept a blank entry. Try leaving it empty.
2. Read the line under the field. If it says "for order updates only," hold the company to that.
3. Use an authenticator app where offered. It removes the dependence on your carrier.
4. Add a carrier PIN. Many mobile carriers let you set a PIN or password that must be given before the number can be moved.
5. Separate numbers for separate purposes. Some people keep a secondary number for shopping sign-ups, keeping their main number for banks and people they know.

Our privacy notice lists exactly what we store about you, and a phone number is not part of it.

Questions people ask

Is it safer to sign in with a text-message code than with just a password?

Yes, a second factor is better than none. An authenticator app is stronger still, because it cannot be redirected by moving your phone number.

Can a shop share my number with advertisers?

Depending on where you live and what you agreed to, yes. The privacy notice should say whether customer data is shared or matched with advertising partners.

What should I do if I start getting spam after signing up somewhere?

Opt out of marketing in the account settings, report the messages as spam, and consider whether the number was shared beyond that company. Changing the number is a last resort, but sometimes the right one.