Trace Anonymous Calls in Germany: The Fangschaltung
Short answer
In Germany, you can have anonymous threatening or harassing calls traced with a Fangschaltung. You apply in writing to your own phone provider, which must then tell you which lines future calls come from, even with a hidden number. It only covers calls after your application and, according to the regulator, it is not free. Threats and stalking should also be reported to the police.
The phone rings at night, the screen says “Unbekannt”, and the person on the line stays silent or makes threats. By the third time in a week it is no accident. Germany has a specific procedure for this that many people only know from crime dramas: the Fangschaltung, literally “trap circuit”. Its legal name is “notification of incoming connections”, and it is set out in section 14 of the TDDDG, Germany’s telecoms privacy law.
What a Fangschaltung does
A Fangschaltung is information from your phone provider about the lines from which certain calls reach you. It works even when the caller hides their number. For this purpose your provider may process the line identifiers and the holders’ names and addresses, along with the time of the calls, and pass that on to you.
The Bundesnetzagentur, Germany’s telecoms regulator, has no general power to find out where calls come from. That makes the Fangschaltung one of the few ways for a private person to identify someone hiding behind a suppressed number.
When you can get one
The law sets one condition: you must credibly explain that threatening or harassing calls are reaching your line. Credibly means a coherent account with concrete details. You do not need formal proof.
Think repeated silent calls. Calls in the middle of the night. Insults, threats. A single wrong number does not qualify. Marketing calls are a special case, because German law forbids marketing callers from hiding their number at all (section 15(2) TDDDG). For those, report to the regulator instead; see reporting scam calls in Germany.
The procedure is tied to German lines. If you have a German landline or mobile contract, you apply to that provider. If the harassing calls reach a foreign SIM you use while living in Germany, your provider sits abroad, and the German procedure is aimed at German providers. In that case check the rules of your provider’s country.
How to apply
- Log the callsNote the time, duration and content of every call, ideally in a simple table.
- Apply in writingWrite to your own phone provider, describe the threatening or harassing calls, ask about the cost.
- Keep loggingOnly calls after the application count. Record each new call with its time.
- Narrow it downTell the provider which calls you mean, by date and time, so it can give targeted information.
- Receive the resultThe provider tells you the line identifier, name and address behind those calls.
Source: Section 14 TDDDG; Bundesnetzagentur, information rights on phone numbers
The application must be in writing. A short German text is safest:
„Hiermit beantrage ich die Mitteilung ankommender Verbindungen nach § 14 TDDDG für meinen Anschluss 0… . Seit dem [Datum] erhalte ich wiederholt belästigende Anrufe mit unterdrückter Rufnummer, zuletzt am [Datum, Uhrzeit]. Bitte teilen Sie mir mit, welche Kosten entstehen.“
In English: “I hereby apply for notification of incoming connections under section 14 TDDDG for my line 0…. Since [date] I have repeatedly received harassing calls with a hidden number, most recently on [date, time]. Please tell me what this will cost.”
The fourth step matters more than it looks. The law only allows disclosure if you first narrow the calls down by date, time or other suitable criteria. This stops the procedure being abused to identify everyone who called during a period. Your call log is therefore the most important tool in the whole process.
The information is cross-network. If the call comes from another German network, every provider involved must give your provider the information it needs, as far as it has the data, so you do not have to contact each company yourself.
Costs and limits
The regulator states plainly that a Fangschaltung is chargeable and only works for future calls. Your provider sets the price, so ask first.
Three situations where it reaches its limits:
- Earlier calls. Anything before your application is not covered.
- Calls from abroad. Since December 2022, German networks must suppress German numbers on calls coming from foreign networks. How far such calls can be traced depends on what data the providers involved hold; they only have to cooperate as far as they have it.
- The caller is told. The holder of the line the calls came from is normally informed that information was given. Only if you explain in writing that this could cause you serious harm, and that harm outweighs the caller’s interests, can the notice be skipped.
The last point is sensitive. In cases of stalking or domestic violence, telling the caller could make things worse, which is why the law allows the notice to be dropped. Spell out your reasons clearly in the application.
Why there are more anonymous calls since 2022
Many people in Germany notice more calls showing “unknown” than a few years ago. You are not imagining it. The regulator predicted exactly this when a new rule took effect on 1 December 2022: calls from foreign networks that display a German number must have that number suppressed. Many spoofed calls were routed through foreign networks, and they now appear as anonymous.
So not every anonymous call is harassment. Hiding your number is legal, and people with good reasons do it. A Fangschaltung makes sense once there is a pattern: repeated calls, threatening or harassing content, clusters at certain times.
Fangschaltung, police report or blocking: which fits
| Criterion | Fangschaltung | Police report | Reject anonymous calls |
|---|---|---|---|
| Gives you the caller's name | no, but police can investigate | ||
| Covers past calls | depends on available data | ||
| Costs money | yes, per the regulator | ||
| Suitable for threats | only as an add-on | ||
| Suitable for marketing calls | hardly |
Threats, extortion and stalking belong with the police. The regulator explicitly mentions a report against persons unknown as an option, because the police can in some cases identify the line holder themselves. A Fangschaltung and a police report do not exclude each other; the result of the trace may be what makes a report possible in the first place. For emergencies, dial 110.
If you simply want peace, the easiest solution is to stop anonymous calls getting through. Under section 15 TDDDG and section 120 of the Telecommunications Act, you must be able to reject calls with a hidden number easily and free of charge. Our guide to blocking spam calls shows how on routers and phones. The downside: anyone who hides their number for good reasons will not get through either.
When nothing else helps
The last resort is a new number. According to German police advice, changing your number is usually free for victims of phone fraud. Do not list the new number in the phone directory; under section 17 TDDDG you are only listed if you apply.
To see whether a call with a visible number came from abroad, a mobile or a landline, use our number checker. For calls that ring only once, read about the one-ring scam.
Companies whose staff are threatened or probed for information by phone should not treat it as a one-off. Such calls can be part of social engineering, and cyber security support can help set up procedures against it.
Start a simple log today and note every anonymous call with its time and content. Without it, neither a Fangschaltung nor a police report will get far.
Classify a number: Uses the prefix to tell whether a number is landline, mobile, a special-rate range or foreign, and roughly what calling back costs.
Questions people ask
How much does a Fangschaltung cost?
The Bundesnetzagentur states that a Fangschaltung is chargeable. Your provider sets the price, so ask before you apply.
Can past calls be traced?
No. Section 14 TDDDG only covers calls and call attempts made after you applied. Earlier calls are not included.
Will the caller find out?
Usually, yes. The holder of the line the calls came from is informed. That can be skipped if you explain in writing that the notification could cause you serious harm.
Can I apply in English?
The law only requires a written application, not a language. A short application in German avoids misunderstandings, and this article includes a template with an English translation.
