Posted on 03/08/26 09:13 am
Most people worry about their email address when signing up for a new app. Your phone number, though, is doing far more damage quietly in the background. It is one of the most persistent identifiers you own — harder to change than an email, tied to your real identity, and passed around an industry most people have never heard of: data brokers. Understanding how that pipeline works is the first step to slowing it down.
Data brokers are companies whose entire business model is collecting personal information about you and selling it to anyone willing to pay. They gather your name, home address, phone number, email, relatives, income estimates, and more — without your knowledge or meaningful consent. Most people have never heard of them, yet they know more about you than your closest friends.
The scale is genuinely significant. California's data broker registry lists hundreds of registered brokers, but industry estimates put the true number above 4,000 when including resellers and companies that broker data as a secondary business — and that is just the ones operating in a regulated state. The data broker industry is worth hundreds of billions of dollars globally, a figure that underlines why your personal details are treated as a commodity rather than private information.
The route from "you just signed up for an app" to "your number is in a broker's database" is shorter and more automated than most people expect.
When an app asks for your phone number during sign-up, you are not just handing over a contact detail — you are often agreeing, buried in the terms of service, to data-sharing arrangements that few people ever read. Most consumers unknowingly consent to this when they tap "I agree" and move on. Every time you install a free app that requests your number, that data has likely been sold multiple times over before you have even used the app twice. The phone number is particularly valuable to brokers because it is a stable, unique identifier that links records across multiple sources.
Data brokers also pull from public records — voter registration, property deeds, court filings — as well as social media profiles, loyalty programmes, online purchases, and app usage data. Once your number appears in even one of those sources, it gets cross-referenced and merged with everything else. Other brokers then buy that merged data. Eventually, people-search sites publish it. Because this entire process is automated, your information can appear on sites you have never visited and never interacted with.
No single data point gives brokers a complete picture. But the moment your phone number connects with your email, your name, and your approximate location — all of which flow from a typical app sign-up — the pieces lock together quickly. Brokers then sell you as a product to other businesses, using AI-assisted inference to add attributes not directly collected. What started as a phone number used for a one-time verification code ends up as part of a detailed profile that is bought and sold repeatedly.
This is worth reading alongside our deeper look at what your phone number reveals when you sign up for a new app, which covers the metadata dimension in more detail.
Your email is almost infinitely replaceable — you can create a new one in minutes. Your phone number is far stickier. It is tied to your bank, your two-factor authentication logins, and potentially years of app accounts. Changing it is a significant administrative undertaking, and even when you do, your old number carries a history that does not simply disappear. As we explored in our post on why your real phone number is a risk every time you sign up, that persistent link to your identity is precisely what makes it so attractive to brokers and marketers alike.
The era of maintaining a single permanent phone number for every aspect of your digital life is effectively over for privacy-conscious users. Treating your primary number like a home address — closely guarded, shared only with people who genuinely need it — while using virtual numbers for routine sign-ups is increasingly the sensible default rather than an edge-case behaviour.
There is a frustrating quality to this problem that makes a one-off opt-out insufficient. Brokers refresh their databases regularly. Even if a listing disappears once, it may return when new records match your name and address again. This is especially true of phone numbers if you continue signing up for new apps with the same number, effectively replenishing the very data you just tried to remove.
The cycle is also compounding. Every new platform you join with your real number creates a fresh data point for brokers to harvest. We wrote about exactly this pattern in one number for every app quietly compounds your risk — the more services attached to a single number, the more valuable and exposed that number becomes as a cross-platform identifier.
You cannot realistically opt out of every data broker individually. Hundreds of brokers are registered in California alone, and contacting each one manually is not a realistic expectation for a normal person. Legislation like California's DELETE Act is a step forward, but it only reaches registered brokers in one state and takes time to enforce.
The more durable approach is to treat your real phone number like a home address: you give it to people and institutions who genuinely need it long-term, and you use something else for everything else. When you sign up for a new platform — especially one you are unsure about — using a virtual number for the SMS verification step means your real number never enters that app's data pipeline in the first place. There is nothing to sell, nothing to aggregate, and nothing to cross-reference.
Not every virtual number achieves this cleanly. Free public SMS inboxes are shared with hundreds of other users, meaning received codes are visible to anyone and the number has already been cycled through countless other sign-ups. That introduces its own risks and frequently gets those numbers blocked by platforms that have seen them before.
The important technical distinction is carrier registration. Apps that screen for virtual numbers are specifically looking for VoIP lines that are not registered with a real carrier. A non-VoIP, carrier-registered number sidesteps that filter entirely because it looks and behaves like a legitimate mobile number to the platform's verification system. That is the difference between a number that bounces and one that works first time.
SMS Pin Verify provides carrier-registered US and UK numbers designed to pass exactly these kinds of checks. Numbers are available on a per-use basis from a few cents, or as rentals of up to 25 days when you need a number that persists for a little while — useful if a platform sends follow-up codes or if you expect to re-verify shortly after signing up. There is no mandatory sign-up for free-tier numbers, crypto payments are accepted for those who want to keep the transaction itself private, and the service supports verification across 285+ countries. It is straightforwardly designed for the situation described in this article: keeping your real number out of systems that will monetise it.
The honest takeaway here is not that you need to become a privacy extremist. It is that the default behaviour — handing your real number to every app that asks — has a real cost that most people only discover later, when the spam calls arrive or when they check a people-search site and find their details listed publicly.
Treating your phone number with the same care you would apply to your home address is a realistic, proportionate response to how the data ecosystem actually works today. Using a virtual number for sign-ups is not a paranoid overreaction — it is the sensible modern habit, and it costs less than a cup of coffee.