Call From Disconnected Number? Out Of Service Phone Spoofing


On average, Americans receive almost 30 spam calls per month. If you tried to call back the number, you might find it’s reported as out of service. This can be super annoying, especially if you’re waiting for an important call. What causes a call from disconnected numbers, and is it dangerous to call back?

As a general rule, a call from a disconnected number is a robocall. Automated phone systems frequently use caller ID spoofing to place telephone calls from out-of-service numbers to prevent callbacks. While recipients can defend against spoof calls, scammers have various motives for robocalling.

Finding and maintaining a list of disconnected numbers can even be the primary goal of robocalling campaigns. Read on to learn how to safely call back a suspected spoofed number, as well as a few tips to stop robocalls from reaching you.

Angry man with smartphone calling back a disconnected number

What Is Caller ID Spoofing?

Caller ID Spoofing is a malicious act of falsifying a caller’s information to steal money or sensitive information. It involves the masking of a callers’ numbers or calls station to disguise the real identity. Criminals also use real company numbers or neighbors to gain the recipients’ trust.

Caller ID started as far back as 1968 when Theodore George Paraskevakos invented a device capable of identifying and decoding pulses representing the phone numbers of an incoming call. George’s invention could also determine the three-digit area code.

The device was aimed at revealing the identity of a calling party and not perpetrate malicious attacks. But scammers now mask their ID with Voice over IP (VoIP) systems or commercial services for internet calls. VoIP systems allow users to use display any desired phone number as the caller IDs. Attackers or telemarketers can easily spoof an out-of-service or disconnected number.

Why Do Robocallers & Scammers Call From Disconnected Numbers?

Robocallers and scammers often call from disconnected numbers to stop the recipient from calling them back. Scammers hide their actual phone numbers while they attempt to steal information for financial gain. Robocalling systems are generally used to gather intelligence on a large number of phone numbers.

Scammers use disconnected numbers to avoid tracking by recipients, customers, or the phone company. After defrauding a target, it’s expected that some attempts will be made to track and apprehend the perpetrators. So, cyber criminals employ spoofed out of service or disconnected numbers to hide their identities.

Checking large lists of phone numbers is time-consuming for a human. Automatic dialing systems will robocall telephone numbers to verify that

  • the number is active
  • has a human who answers unsolicited calls or
  • start a transfer to a telemarketer or worse, a scam
Man with smartphone confused by a call from disconnected number

Is Caller ID Spoofing Legal?

Caller ID Spoofing is legal in many countries. In the US, under the Truth in Caller ID Act of 2009 and the Anti-spoofing Act of 2017, spoofing is illegal when the intent is harmful, wrongfully obtains valuables, or defraud. Companies offering spoofing services are often fined or blocked.

The anti-spoofing legislation bill (s.134) was introduced to the house by Senators Fischer, Blunt, Nelson, and Klobucher on January 12, 2017. The bill’s purpose was to extend the Federal Communications Commission (FCC) authority to address cases of spoofing in the US. The bill also empowers the Commission to combat international spoofing involving text messages and voice communications. The legislation also gives FCC the authority to levy criminal fines and penalties against culprits.

The anti-spoofing Act of 2017 prohibits both individuals and entities from transmitting the wrong caller ID intended for harmful acts against the receiver. Under the Act, the FCC can penalize the violators with a fine of $10,000. However, scammers ignore the rule, especially if they’re from countries outside the FCC jurisdiction. Many of them also continue their operations with the hope of not being caught.

Does a disconnected number ring?

A disconnected number doesn’t ring. When you call a disconnected number, you’ll hear the announcement that your call cannot be completed or that the number you’re calling is incorrect or out of service. The intercept operator may also announce that the number has been disconnected.

However, if the number is non-existent, there will be several beeps or a recorded message since there’s no valid identity tied to the number. In some cases, scammers produce a fake disconnected tone or message to deceive the caller into thinking that their number has been disconnected.

How To Call Back A Suspected Spoofed Number

Calling back a suspected spoofed number is possible but not recommended.

You can use the vertical service code *67 to hide your number for a single call. Dialing this code on your keypad before adding the suspected spoofed number will mask your cell phone number. The scammer will not see your numbers when receiving the calls. They’ll see your number as blocked or private.

Another way of calling back a spoofed number is by using a burner phone. Burner phone lines prevent an attacker from receiving your regular line. Burner phone or burner apps can be bought anonymously or pseudonymously. After a short use, a burner line can be discarded along with any problems that arise from calling back a spoofed number.

Man with smartphone answering a call from disconnected number

How To Stop Robocalls From Any Number Including Disconnected Numbers

If you don’t want to receive unwanted calls from disconnected numbers or robocalls, you can do the following:

Stop putting your actual number on the internet.

Putting your real telephone number on the internet makes you vulnerable to robocalls and malicious calls. If you must add a phone number to an online account, use a personal burner phone number or work phone to reduce access to your personal life.

Use call screening

Call screening is a process of selecting the calls you accept or reject based on the caller ID.

One of the simplest ways to screen your calls is to enter phone numbers in your contacts and only accept calls from the registered numbers.

Another way is to enable the call screening feature in your smartphone. Once enabled, it evaluates every call to determine if the number is unknown, blocked, or disconnected. With such information, you can decide whether to answer the call.

Many phones have call screening features. But you can also get the Google call screening for your phone. With the app, Google Assistant will automatically screen calls that aren’t stored in your contacts list.

Apart from the Google call screening app, there are other call screening apps and services to use on your phone.

Install a robocalling blocker

Several robocall blocker apps can help keep incoming calls from disconnected numbers away from your phone.

For mobile phone users, take a look at some of the following services that stop robocalls.

On the budget-friendly side, take a look at Truecaller for call screening.

 Call Control Home can help protect your landline from scam calls.

Register with the National “Do Not Call” registry

The National Do Not Call registry keeps your number safe from telemarketers. Once you add your number to their list, you’re legally off-limits for telemarketers. Moreover, you’re free to remove your phone line from the registry at any time.

Block unwanted calls with carrier tools

You can use premium tools from your telephone company to at least reduce robocalls.

A service provider like AT&T, Verizon, T-Mobile & Sprint offers opt-in solutions to screen and block unwanted calls. Most of the options are premium functions which are additional fees charged to your phone bill. This can be an effective way to stop calls from spoofed, disconnected numbers.

Mike Chu

Mike is a web developer and content writer living as a digital nomad. With more than 20 years of devops experience, he brings his "programmer with people skills" approach to help explain technology to the average user. Check out his full author bio by clicking here.

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