Regulations • Last Updated 9/29/2023

What is Spoofing and Why Does it Matter?

Spoofing is a tool scammers use to get information or bypass call blockers and pose as bank, business, or government agency

By Josh Whitaker

Call Spoofing banner graphic

When caller id was first introduced in the late 80s, it was a complete gamechanger. It was the first time the average phone owner could screen calls, and weed out the bothersome spam that started flooding the lines.

Fast forward to today, and spammers and scammers alike have found a way to use caller ID display to their advantage. It’s called number spoofing, and it can be more than just annoying, it can be downright harmful. So what is a spoof call, and how do you better protect yourself from fake numbers appearing on your phone screen?

What is a Spoof Call?

Number spoofing is when a caller uses technology to display a different caller ID number than the one they are calling from to mask their true identity. While spoofing a phone number can be used for legitimate and legal reasons, it’s most commonly used for malicious purposes.

Scammers or telemarketing companies often use something called neighbor spoofing. As the name would suggest, neighbor spoofing is when the number displayed on the recipient’s caller ID appears to be coming from a local number. People often trust local numbers, and are more likely to answer the phone.

Another shady tactic used by scammers is spoofing a number to make it appear the call is coming from a trusted company or government agency. This is just another way to increase the likelihood that someone will answer the call, and trust the person on the other end of the line.

Spoofing a phone number is only illegal if the act is malicious in intent. For example, falsifying a number to scam or defraud the person on the other end of the phone. If caught, the guilty party can find themselves facing a penalty of up to $10,000 for each violation.

However, according to the Truth in Caller ID Act, there are instances when number spoofing is perfectly legal. For example, a medical professional may use their cell phone to call a patient, but have their office number appear on the screen. Since there is no intent to defraud or cause harm, this instance of number spoofing is legal.

Reporting Caller ID spoofing

Unfortunately, the FCC does not resolve individual complaints. However, if your number is being spoofed, or you're receiving calls from a spoofed number, you can still submit a report to help provide valuable information.

How Spoofing Caller ID Works

Historically, number spoofing was a tall order with a hefty price tag. It required in-depth knowledge of telephony, and some expensive equipment to get the job done.

Today, especially with the emergence of VoIP, spoofing a caller ID is easier than ever. In fact, softwares and VoIP companies offer easy number spoofing with little cost attached. More importantly, setting up a fake number doesn’t require any extensive knowledge of telephony.

So, how does number spoofing work?

First, it’s important to note that the responsibility of caller ID falls on the number making the call, not the number receiving it. That means the caller information displayed on the phone screen is passed from the caller to the receive, making it easy to spoof.

In the more traditional plain old telephone system (POTS), the information is passed using frequency shift keying (FSK) during the first two rings of the call. With personal home or cell phones, the information being passed is usually handled by the phone carrier.

On the other hand, business or VoIP phone systems are usually given access to the primary rate interface (PRI). Meaning, the information being passed is now the responsibility of the private branch exchange (PBX). Once you have access to the PRI, you can begin to spoof numbers.

Tracing Spoofed Calls

Unfortunately, there’s no guaranteed method for tracing a spoofed call. The reason being, modern technology has made it fairly easy to spoof numbers without leaving much of a trail. So, unless you’re somehow able to employ the help of your phone carrier or law enforcement, there’s not much you can do.

What to do if You Experience Spoofing

It’s important to stay vigilant when it comes to your personal information. If you are receiving a call from a number you don’t recognize, or something seems fishy about the caller ID being displayed on your phone, it may be in your best interest to avoid answering the call all together.

If, for any reason, you have to or choose to answer, don’t provide any private information. Avoid divulging things like your name, social security number, credit card number, or anything else that scammers can use to defraud or harm you.

If you’re expecting a call, but still aren’t sure, immediately hang up the phone and call the official number listed on the website or statement. They will be able to help you, and let you know if the call you just received is legitimate or not.

How scammers use spoofing

For scammers, spoofing is a tool for getting information or bypassing call blockers. Typically, scammers use spoofing to pose as a bank, business, or government agency in order to trick people into giving up personal or financial information.

Usually, scammers accomplish this by mimicking invalid, inactive, or unassigned phone numbers. The process is fairly simple, and utilizes the same technology that allows people to use standard phone numbers over Skype or Google voice.

These phone scams are frequently conducted using robocalls—automated phone calls that deliver pre-recorded messages.

According to the IRS, scammers posing as tax collectors snagged about $26.5 million from people using spoofed phone numbers.

Although it’s uncommon, some telemarketers also use spoofing to call people who’ve blocked their real phone number to avoid more calls. This is also illegal. For telemarketing, businesses are required to use the phone number associated with the company and that can be called to request that they stop calling.

Calls that you think are from spoofed phone numbers can be reported to the FCC.

Spoof detection

Fortunately, recent regulation has been passed that allows telephone carriers to block all calls from invalid numbers, inactive, or unassigned phone numbers. If carriers choose to enact that policy, most number spoofing used by scammers should be stopped.

About Telnyx

Telnyx delivers voice, messaging, and more for applications and next-generation communications companies. Telnyx provides advanced CNAM querying through direct database lookup for improved fraud detection and call context. Contact our customer success team to learn more.


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