Stop spam calls: how to block foreign prefixes
National filters have stopped a lot of spoofed local numbers. Real foreign calls still get through: +44, +33, +91 and many more. Here is a practical way to block them without giving up your privacy.
In this guide
The spam call problem
Unwanted calls have become a daily nuisance: foreign numbers, investment scams, aggressive call centers and, above all, numbers that looked local on the display while actually originating abroad.
That technique is called spoofing: the caller fakes the number you see. For years it was one of the main tricks used to make people answer.
What anti-spoofing filters fixed
In Italy, AGCOM activated a national filter that automatically blocks calls from abroad that pretend to be Italian numbers (+39). Similar anti-spoofing measures exist or are arriving in other countries.
Those scams where someone called from London or Hong Kong while showing a believable local number no longer get through. That is a major win: spoofing local numbers was one of the most effective ways to fool people.
What still gets through: real foreign prefixes
Anti-spoofing filters do not block genuine foreign calls. If someone really dials from the United Kingdom (+44), France (+33), India (+91) or Hong Kong (+852), the call is real and it rings.
That is the spam that still bothers people today: not a fake local number, but a real international prefix. Stopping it needs an extra step on the phone or with your carrier.
Practical options
It depends on your carrier and phone. Some options work well, others only partly.
- Carrier firewall. Some operators offer an account setting that mostly lets local numbers through. If you have it, use it: simple and no extra app required.
- Built-in Phone app. On many Android phones the native block list mostly handles single numbers. Foreign spam keeps changing the last digits: blocking one number at a time does not scale.
- Third-party apps. Truecaller, Hiya and similar tools often rely on shared spam databases. They can work, but they ask for many permissions, sometimes replace the Phone app and move decisions and data outside your control.
- Local prefix blocking. A privacy-first app like PrefixBlocker puts the rules in your hands: countries, prefixes, contacts and groups, all on the phone, with no account and no cloud.
How to do it with PrefixBlocker
PrefixBlocker decides based on how a number starts. Add +34 and you cover all of Spain; add +34 1234 and you cover only numbers that begin that way. You do not type asterisks: the prefix you set is already a "starts with" filter.
The strongest shortcut, if you live in one country and do not need foreign calls: Allow only mode with just your country (for example Italy +39). Local numbers get through, everything else is cut off in one step. Address-book contacts are handled separately in the Contacts tab, so saved family or clients are not lost.
- Set it as the call screener. Android asks for the call screening role so the app can decide on incoming calls locally.
- Choose your strategy. Fast option: Allow only + your country. Selective option: Block mode and list the noisy prefixes (+44, +34, +33, +91...), or tighter pieces like +34 1234 when you need finer control.
- Check foreign contacts. If you have family or work abroad, in Allow only also add those countries, or let saved contacts through from the Contacts tab.
- Use the activity log. Every block shows the rule that caused it, so you can fine-tune quickly.
If you do not want to close all foreign calls at once, start with the Top 15 in Block mode and add more prefixes only if spam keeps coming from there.
Do and don't
Do
- If local calls are enough, use Allow only with your country code: it is the fastest way to cut foreign spam.
- If you need a few countries, add them to the allow list, or block only the prefixes that bother you.
- Check contacts and work abroad before closing a whole country.
- Report spam with your phone or carrier tools when you can.
Never do this
- Do not give personal data over the phone: no serious operator asks for it that way.
- Do not answer just to say no: that confirms the number is active.
- Do not call suspicious numbers back: they may be premium-rate.
- Do not install apps that demand excessive permissions just for a spam list.
Top 15 prefixes to block first
Useful if you prefer Block mode instead of closing all foreign calls. This is not an official ranking: it is a practical list of prefixes that often show up in spam and phone-scam reports, especially for users in Europe.
| Prefix | Country | Risk | Notes |
|---|---|---|---|
+44 |
United Kingdom | Among the worst overall | |
+34 |
Spain | Aggressive call centers | |
+33 |
France | Trading scams and telemarketing | |
+31 |
Netherlands | European phishing and robocalls | |
+32 |
Belgium | Intermittent spam | |
+46 |
Sweden | Rising in recent months | |
+91 |
India | Fraudulent call centers | |
+86 |
China | Mass spam and robocalls | |
+852 |
Hong Kong | Trading and investment scams | |
+48 |
Poland | Fake bank messages and phishing | |
+49 |
Germany | Constant spam | |
+351 |
Portugal | Fake call centers | |
+357 |
Cyprus | Financial scams | |
+371 |
Latvia | Bots and automated spam | |
+372 |
Estonia | Robocalls and phishing |
Full list by region
Use this as a reference. In Block mode pick the prefixes that actually disturb you; in Allow only it mainly helps you see what you are leaving out.
Europe
-
+30Greece -
+31Netherlands -
+32Belgium -
+33France -
+34Spain -
+351Portugal -
+352Luxembourg -
+353Ireland -
+354Iceland -
+355Albania -
+356Malta -
+357Cyprus -
+358Finland -
+359Bulgaria -
+36Hungary -
+370Lithuania -
+371Latvia -
+372Estonia -
+373Moldova -
+374Armenia -
+375Belarus -
+376Andorra -
+377Monaco -
+378San Marino -
+380Ukraine -
+381Serbia -
+382Montenegro -
+383Kosovo -
+40Romania -
+41Switzerland -
+43Austria -
+44United Kingdom -
+45Denmark -
+46Sweden -
+47Norway -
+48Poland -
+49Germany
Americas
-
+52Mexico -
+53Cuba -
+55Brazil -
+57Colombia
Asia, Oceania and Middle East
-
+60Malaysia -
+61Australia -
+62Indonesia -
+63Philippines -
+65Singapore -
+81Japan -
+82South Korea -
+852Hong Kong -
+86China -
+90Turkey -
+91India -
+92Pakistan -
+93Afghanistan -
+94Sri Lanka -
+95Myanmar -
+98Iran
Frequently asked questions
Is an anti-spoofing filter enough on its own?
No. It stops spoofed local numbers from abroad, but not genuine foreign calls. Those need prefix blocking or a carrier filter.
Can I allow only my country and block everything else?
Yes. In PrefixBlocker open Prefixes, choose Allow only and add your country (for example Italy +39). Calls from other prefixes are blocked. Saved contacts are controlled in the Contacts tab.
Can I cut international spam without closing everything?
Yes: stay in Block mode and add only the noisy prefixes, or in Allow only authorize your country plus the few countries you really need.
What does blocking by prefix mean?
The filter matches the start of the number. +44 blocks (or allows) the whole United Kingdom; +44 20 only numbers that begin that way. It is not a single contact entry: it is a range defined by how the call starts.
Why are built-in Android filters not enough?
Many only block single numbers. Spam rotates across thousands of numbers under the same country or the same prefix piece: without a "starts with" filter, the calls keep coming.
Does PrefixBlocker use a shared spam database?
No. You decide the rules. There is no global list marking numbers for you, and the data stays on your phone.
Does it work offline?
Yes. Blocking happens locally. No account and no connection are required to stop calls.
Try PrefixBlocker on Android
Allow only your country, or block the prefixes that bother you, with rules you control and without giving up privacy. Free to try, one-time unlock, no subscription.
Get it on Google Play