Identify unknown phone numbers: How to do a reverse lookup

If you want to identify the caller behind an unknown phone number, there are several ways to do this.

Identify unknown callers: Find phone numbers with an internet search

If you have received a call from an unknown number and want to find out who is behind it, you can start a reverse search on the internet.

• Suitable websites include Das Örtliche or DasTelefonbuch. Enter the phone number here. However, many numbers are not listed because the caller must have given their contact details on the website.

• Another option is to use a classic search engine such as Google or portals such as Tellows or 11880.com. This method is particularly useful for advertising calls, as these numbers often already have several bad reviews. Here, too, simply enter the unknown number in the search field and, once the search has started, you will see who the number is assigned to.

• In addition to websites, there are also special apps such as Truecaller that provide information about the caller. To use these, simply install the app and then search for the number. Please note that such apps can be problematic from a data protection perspective, as they gain access to your address book.

Phone number: Identification via voicemail

To identify the caller behind a number, you can also call their voicemail directly. This way, the phone will not ring and you can hear the voicemail message. The name of the owner is often mentioned here.

• To call the mailbox directly, you need to find out the provider behind the number. You can do this using the area code.

• Then, when you call back, you just need to enter the voicemail code between the area code and the number. This varies depending on the provider. For O2 and E-Plus it is 33, for Vodafone it is 50, and for Telekom it is 13.

• So if it’s a Vodafone number, for example 0174 50 12345678. When calling back, don’t forget to suppress your phone number.

Blocking calls from unknown numbers: How to do it

If you don’t want to receive calls from unknown numbers in general, you can block them. This can be useful for children’s cell phones, for example.

• If you have an iPhone, open Settings and search for “Phone.” Tap on it and then tap on “Silence Unknown Callers.” In the next step, you can activate the option using a slider.

• If you have an Android smartphone, open the phone app, tap on the three dots in the top right corner and select “Settings.” Tap on “Blocked numbers” and activate “Block unknown callers” using the slider if you do not want to receive calls from unknown numbers.

• Important to know: If you activate the blocking function, you will no longer receive any calls from numbers you do not know. This means that you will not only avoid advertising calls, but also important calls may no longer get through. To avoid this, block individual numbers or use smart spam filter apps.