Call ID spoofing: what is it? Easily explained

In connection with telephone numbers and cases of fraud, one often hears the term "Call ID spoofing". In this practical tip, we explain what that is and how you can protect yourself against it.

What is Call ID Spoofing?

Call ID spoofing is a prohibited method of making calls from a fake number.

• A phone number shown on the phone display is not a reliable way to clearly identify the caller.
• Criminals can manipulate telephone connections so that a different telephone number is displayed for the person called. This process is called call ID spoofing.
• The possibility of this criminal act exists not only in non-regulated communication networks such as the Internet, but also in public networks, such as the classic telephone network.
• According to the TKG (Telecommunications Act), call ID spoofing is strictly prohibited.
• There it says namely in paragraph 66: "[...] Other providers involved in the connection may not change transmitted telephone numbers. [...]"
• The reason for this prohibition is, for example, the emergency call: If a caller can no longer speak due to injuries, the number can be traced back so that he can still help. However, this help cannot be guaranteed if the emergency services do not have access to the correct caller information.
• Call ID spoofing is mostly known due to non-compliance with this law, especially since such cases can be reported to the Federal Network Agency.
• It was only in January 2017 that a group was exposed in Cologne, who pretended to be police officers on the phone and then relieved seniors of valuables.

What is Call ID Spoofing? - How it works

The basis for using Call ID spoofing was the introduction of the Call ID.

• This is the identification of a caller using caller information such as the telephone number.
• Criminals exploit this through Voice-over-IP technology (VoIP) or ISDN connections and manipulate the display of the calling number.
• Call-ID spoofing is very easy, especially for VoIP calls, because the "display information" can be changed in advance for calls over the Internet, so that even the calling number does not have to be modified.
• There are separate providers for call ID spoofing ("spoofing services") that give you the option of entering a number or information that should be shown on the called party's display. These services are usually free of charge and are now even available as an app.
• This service provider then also takes care of the transfer of the call. It issues so-called spoof cards, which, like prepaid cards, contain a certain amount of credit for spoofing calls.
• Call ID spoofing was first used in 2004 by hacker Kevin Mitnick.
• Even if spoofing itself is illegal, it does offer a certain added value for collection agencies, journalists or lawyers if this technology is used for investigation or research.
• Call ID spoofing also laid the basis for telephone phishing and "SPIT" ("spam over internet telephony").

What is Call ID Spoofing? - How to protect yourself

Several relatively simple tips will help you protect yourself against Call ID spoofing.

• So it often helps to let the well-known "common sense" prevail.
• When alleged judges, police officers, prosecutors, consumer advocates or pension insurance employees, banks or well-known companies call and ask you to pay money, you should be skeptical and not respond to claims, consumer advocates warn.
• All of these authorities and agencies would never call for money, ask for account information or passwords, or request access to the computer.
• If in doubt, you should inquire after such a call to the authority or the company whether there is anything in the matter described by the caller.
• It is also important to write down the time of the call, important details such as the name of the caller and the account number to which any money claims should be transferred. You should go to the police with that.
• Protection against call ID spoofing is also possible in other ways, for example via the "TrueCaller" app. This identifies unknown numbers that are used by criminals and allows you to simply not answer the call.
• Checking the calling number can also help. Apologize to the suspected fraudster and pick up a second phone. Then dial the number that is calling you.
• If you do not get a busy signal, you should exercise caution, because you are probably exposed to call ID spoofing.
• In addition, you should generally avoid sharing personal information on the phone. Instead, arrange a conversation or a written request to be on the safe side.

In our next tip, we will explain what you can do about telephone terror.