You’ve probably seen it on your own screen. A call comes in from a local area code, maybe even your own prefix, and you pick up thinking it’s the pharmacy or a neighbor. Instead, it’s a recording about your car’s extended warranty. That’s phone number spoofing in the wild. It’s a trick as old as digital telephony, yet it remains one of the most misunderstood parts of how our modern phone system actually functions.
Honestly, the technology behind this isn't even that complex.
It's basically just a mismatch between the data being sent and the reality of the hardware making the call. When you make a call via Voice over IP (VoIP), the system asks you what number you’d like to display. If you have the right software, you can type in anything. 000-000-0000? Sure. The White House? If you want. But before you go trying to prank your old high school rivals, you need to understand that there is a massive difference between "can" and "should," especially with the FCC breathing down everyone’s necks these days.
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How People Actually Spoof a Phone Number Today
Most people think you need to be some sort of elite hacker to spoof your phone number. You don't. It’s actually kind of trivial if you know where to look. In the early days, you needed a specialized T1 line or expensive PBX hardware. Now? There are dozens of apps on the App Store and Google Play—names like Burner, Hushed, or SpoofCard—that handle the backend for you.
You open the app. You pick the number you want to show up on the recipient's caller ID. You dial. The app’s server initiates a VoIP call to the destination, injecting the "fake" number into the caller ID field of the signaling packet.
The SIP Protocol Explained
At a technical level, most of this happens via Session Initiation Protocol (SIP). Think of SIP as the language VoIP phones use to talk to each other. When a call is placed, a "FROM" field is generated. In a perfect world, your carrier would verify that you actually own the number in that field. But the global phone network is a patchwork of old copper wires and new fiber optics. Many older switches just trust whatever the incoming "FROM" field says.
That’s the loophole.
It's a legacy trust issue. Because the original phone system was built on the idea that only massive, regulated utilities would have access to the "brains" of the network, there weren't many built-in safeguards. Once the internet allowed anyone to connect to these switches via SIP trunks, the gates were wide open.
The Legal Reality (and the STIR/SHAKEN Factor)
Is it illegal?
Well, it depends. In the United States, the Truth in Caller ID Act of 2009 is the rulebook. According to the FCC, spoofing isn't inherently a crime. It only becomes illegal if you do it with the "intent to defraud, cause harm, or wrongly obtain anything of value."
If you're a doctor calling a patient from your personal cell phone but you want the office number to show up so the patient can call you back at the right place, you’re fine. That’s a legitimate use case. But if you're pretending to be the IRS to scare someone into buying iTunes gift cards? You're looking at massive fines—sometimes upwards of $10,000 per call.
Why Your Spoofing Probably Won't Work Anymore
The "Wild West" era of spoofing is rapidly closing. You might have heard of STIR/SHAKEN. No, it’s not a James Bond reference. It stands for Secure Telephone Identity Revisited (STIR) and Signature-based Handling of Asserted Information Using toKENs (SHAKEN).
Basically, it’s a digital certificate system.
When a call is made, the originating carrier "signs" the call with a certificate. If the call is spoofed, the certificate won't match, or there won't be one at all. When the call hits your phone, your carrier sees the "unsigned" call and marks it as "Scam Likely" or "Potential Spam." In some cases, the carrier might just drop the call entirely before your phone even rings.
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Big carriers like Verizon, AT&T, and T-Mobile have spent billions implementing this. If you try to spoof your phone number using a cheap web service today, there is a very high chance the person you're calling will see a big red warning on their screen.
Common Misconceptions About Caller ID
People often think caller ID is a secure, verified feature of their phone service. It isn't. It's actually a two-part process.
First, there is CID (Caller ID), which is just the number. Then there is CNAM (Caller Name), which is the text name associated with that number. When you receive a call, your carrier looks up the number in a massive database to find the name. These databases are notoriously slow to update. This is why sometimes you get a new phone number and people see the name of the person who owned it three years ago.
- Spoofing numbers isn't the same as "Ghosting": Ghosting usually refers to hiding your number entirely (showing up as "Private" or "Unknown"). Spoofing is specifically about showing a different number.
- The "Neighbor" Scam: This is a specific type of spoofing where scammers use your own area code and the first three digits of your number. They do this because data shows you are 3x more likely to pick up a local-looking number.
- Police Spoofing: This is a very real, very dangerous trend where scammers spoof the local precinct's non-emergency line. It’s highly effective and highly illegal.
Practical Steps and Protection
If you actually need to protect your privacy without breaking the law or getting flagged by STIR/SHAKEN, there are better ways to go about it than raw spoofing.
1. Use a Secondary Number Service.
Instead of spoofing a fake number, use a service that gives you a real second number. Google Voice is the most famous example. It’s free, it’s tied to your Google account, and because it’s a legitimate registered number, it won't get flagged as spam. You can make calls from the Google Voice app, and the recipient will see your Google Voice number, not your private cell digits.
*2. The 67 Trick.
It still works. Mostly. Dialing *67 before the number you want to call will block your caller ID on the recipient's end. They will see "Private" or "Restricted." It’s not spoofing—you aren't providing a fake number—you're just withholding yours. Just keep in mind that many people (myself included) never answer "Private" calls.
3. Use Integrated VoIP for Business.
If you run a business, don't try to "hack" your way into showing the office line. Use a proper VoIP provider like Nextiva or RingCentral. These services allow you to "verify" your ownership of a business number. Once verified, you can legally and reliably show that number on caller ID when calling from any device, including your laptop or mobile phone.
What to do if someone is spoofing YOUR number
This is a nightmare scenario. You start getting hundreds of calls from angry strangers telling you to "stop calling them." This is called "Joe Jobbing."
Basically, a scammer has chosen your number at random to be their mask for the day. There isn't much you can do technically to stop them, because they aren't actually using your phone line; they're just typing your digits into a computer halfway across the world.
Usually, these "attacks" last about 24 to 48 hours before the scammer rotates to a new number. Your best bet is to change your voicemail greeting to something like: "Hi, if you're returning a call from this number, please be aware that my number is currently being spoofed by scammers. I did not actually call you." Then, just wait it out.
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Actionable Next Steps for Privacy
If you are looking into how to spoof your phone number because you want to keep your personal life private, stop looking at "spoofing" apps and start looking at "virtual number" apps.
- Download Hushed or Burner: These apps give you a disposable number for a few dollars. It's cleaner, more reliable, and won't get you in legal trouble.
- Check your own "Spam" status: If you think your legitimate number is being wrongly flagged as spam by carriers (which happens!), you can visit sites like https://www.google.com/search?q=FreeCallerRegistry.com to register your number with the major US wireless carriers.
- Enable "Silence Unknown Callers": If you're on iPhone, go to Settings > Phone > Silence Unknown Callers. On Android, it's usually in the Phone app settings under "Spam and Call Screen." This won't stop people from spoofing you, but it will stop you from being bothered by everyone else doing it.
The reality of the phone network in 2026 is that it's a battleground. Carriers are finally fighting back against unauthorized number manipulation. While the "how-to" of spoofing remains simple, the "why-you-shouldn't" has never been more compelling. Protect your identity by using verified tools rather than trying to trick an increasingly smart network.