Every country sets its own rules for what may appear as caller ID. Some only require that the number is valid and diallable. Others restrict which number ranges may be presented on international calls, require local numbers for telemarketing, or block calls that present domestic mobile numbers from abroad. This hub summarises the principles that apply almost everywhere, then links to a detailed page for each of the 20 markets we cover in depth.
Key takeaways
- Almost every country requires a valid, diallable caller ID that you are authorised to present.
- Regulators increasingly block or relabel international calls that present domestic numbers.
- The US and Canada use STIR/SHAKEN; France runs a comparable authentication scheme.
- Some countries require dedicated telemarketing prefixes, such as 0303 in Brazil.
- Each country page below lists the regulator, presentation rules and the date our team last reviewed it.
On this page
Principles that apply almost everywhere
- The number must be valid and diallable. It should be a real number in E.164 format that can receive calls. Regulators in the UK, Germany, France and Australia say so explicitly.
- You must be authorised to present it. Either you hold the number, or the holder has authorised you. Presenting a number you have no right to use is prohibited in nearly every market.
- It must not be a premium-rate or unassigned range. Presenting premium numbers to induce callbacks is a known fraud and is blocked widely.
- Withholding is allowed, hiding is not. Callers may usually withhold their number (privacy), but telemarketing rules in many countries require a number to be presented.
- International calls with domestic CLIs are scrutinised. More regulators now require or permit networks to block international calls presenting domestic numbers unless the caller is legitimately roaming.
Regulatory trends to plan for
Network-level CLI validation
The UK (Ofcom), France (ARCEP) and Germany (BNetzA) have all moved toward network-level checks that block or strip calls from abroad presenting domestic numbers. Ireland and others are following. Expect the same trend in more European and Asia-Pacific markets.
Cryptographic authentication
The US and Canada use STIR/SHAKEN. France has implemented its own MAN (Mécanisme d'Authentification des Numéros) based on the same standards. Others are studying similar frameworks. Read STIR/SHAKEN for Call Centers Outside the US.
Dedicated telemarketing ranges
Some countries assign specific prefixes for telemarketing so recipients can recognise it. France designated ranges for automated calls, and Brazil requires telemarketing calls to use the 0303 prefix. Check the country page before you plan a campaign.
Country summaries
The table below lists the regulator and the date our team last reviewed each summary. Each country page includes number formats, mobile and fixed prefixes, presentation rules, common SIP errors and FAQs.
The CLI must be a valid North American number you are entitled to use. FCC rules require telemarketers to transmit a number that can be called during business hours to opt out, and carriers block calls presenting invalid, unallocated or do-not-originate numbers outright.
United States CLI routesOfcom General Condition C6 requires the CLI to be a valid, dialable number that identifies the caller and that the caller may use. Networks block calls with invalid CLIs, and since 2023 they block calls from abroad that present UK geographic numbers unless the call is genuinely from a UK customer. Ofcom has consulted on extending this to UK mobile CLIs.
United Kingdom CLI routesUnder CRTC Telecom Decision 2018-484, carriers block calls whose caller ID does not conform to the numbering plan. Telemarketers must display a number that can be called back to reach the caller or opt out, and must not suppress it.
Canada CLI routesThe Reducing Scam Calls and Scam SMs industry code requires carriers to block calls presenting invalid, unallocated or unused numbers. Calls from overseas that present Australian mobile numbers are checked against roaming records and blocked when the subscriber is not actually abroad.
Australia CLI routesThe Telecommunications Act (TKG) requires the presented number to be valid and assigned to the caller. Since December 2022, networks must suppress German numbers on calls arriving from abroad, except genuine mobile roaming, so German CLIs on international traffic display as “unknown”.
Germany CLI routesSince January 2023, professionals making telemarketing calls must present a number from the ARCEP ranges reserved for them: 0162, 0163, 0270, 0271, 0377, 0378, 0424, 0425, 0568, 0569, 0948 and 0949. Mobile numbers may not be used for automated calling systems.
France CLI routesSince June 2023, the General Telecommunications Law requires prior consent for unsolicited commercial calls, and callers must present an identifiable number. Spain has introduced a dedicated 400 range for commercial calls, and operators block calls from abroad that falsely present Spanish numbers.
Spain CLI routesAGCOM’s anti-spoofing rules require operators to block calls from abroad that present Italian fixed numbers, and from November 2025 Italian mobile numbers, unless the mobile caller is genuinely roaming. The Registro Pubblico delle Opposizioni covers fixed and mobile numbers.
Italy CLI routesThe Telecommunications Act requires a valid, assigned CLI and forbids suppressing it on telemarketing calls. Since July 2021, telemarketing to consumers needs prior consent unless the person has been a customer within the past three years. Dutch operators increasingly filter calls from abroad that present Dutch numbers without authorisation.
Netherlands CLI routesBIPT numbering rules require a valid assigned number, and marketing calls must not suppress it. Consumers can register on the “Do Not Call Me” list (Bel me niet meer / Ne m’appelez plus), which telemarketers must check. Belgian consumer law also requires the caller to state their identity and the commercial purpose at the start of the call, and the Data Protection Authority treats call lists as personal data under the GDPR.
Belgium CLI routesThe revised Telecommunications Act obliges providers to combat CLI manipulation, including filtering calls from abroad that present Swiss numbers without authorisation. Directory entries marked with an asterisk must not receive advertising calls.
Switzerland CLI routesSuppressing or falsifying the CLI on advertising calls is an administrative offence under the TKG 2021. Consumer advertising calls require prior, documented consent, and the Robinson list maintained by the Chamber of Commerce is a further opt-out.
Austria CLI routesPTS numbering rules require valid assigned numbers. Consumers can opt out via NIX-Telefon, and since September 2022, contracts concluded on a trader-initiated telemarketing call are only valid once the consumer accepts them in writing.
Sweden CLI routesJapanese carriers display the presented number when it is a valid MIC-allocated Japanese number. Calls arriving from abroad are commonly flagged as international, and MIC has pressed carriers to curb international calls that falsely present Japanese numbers.
Japan CLI routesSince March 2022, Anatel has required active telemarketing calls to use the 0303 prefix so recipients can recognise them. Anatel also blocks companies that place very high volumes of very short calls, a measure aimed at robocalls.
Brazil CLI routesCallers must present a valid number. Consumers can register on REPEP, Profeco’s opt-out registry, and telemarketing to registered numbers is prohibited. Telecom regulation moved from the IFT to a new regulator in 2025, so check current guidance with counsel.
Mexico CLI routesCallers must present a valid number. Law 26.951 created the Registro Nacional No Llame, and telemarketing to registered numbers is prohibited. ENACOM administers the numbering plan.
Argentina CLI routesTDRA telemarketing regulations require marketing calls to come from numbers registered in the company’s name, not personal numbers, and restrict them to set hours with limits on repeat calls. Recipients can register on the national Do Not Call Registry. Only licensed operators may provide VoIP calling services.
United Arab Emirates CLI routesCLI presentation depends on the terminating operator, and some mobile networks replace international CLIs. The SIM Registration Act of 2022 ties every mobile number to a verified identity, which has raised scrutiny of unknown numbers.
Philippines CLI routesICASA numbering regulations require a valid assigned number. Under the Consumer Protection Act, direct-marketing calls are limited to set hours, and POPIA section 69 requires consent for electronic direct marketing to people who are not existing customers.
South Africa CLI routesChoosing which number to present
| Option | When it works | Watch out for |
|---|---|---|
| Local DID in the destination | Outbound to consumers; best answer rate in most markets | Must be a number you hold; some countries restrict outbound use of local DIDs from abroad |
| Your home-country number | B2B calls, existing customer relationships | Lower answer rate on consumer calls |
| Toll-free number | Service callbacks | Not presentable as CLI in every country |
| Withheld | Rarely appropriate for business | Very low answer rate; prohibited for telemarketing in many countries |
A local DID number is the most common choice for consumer outbound. Ensure it can receive calls, so customers who call back reach you. Use the E.164 formatter to check numbers before loading them into your dialer.
Regional differences at a glance
North America
The US and Canada share the North American Numbering Plan (+1), so number formats look identical, but regulation differs. Both require STIR/SHAKEN on IP networks. The US adds the TCPA, the Telemarketing Sales Rule and state laws; Canada has the CRTC's Unsolicited Telecommunications Rules and the National DNCL. See United States and Canada.
Europe
EU countries implement the ePrivacy rules nationally, which is why telemarketing rules vary so much. Germany requires prior consent for marketing calls to consumers and forbids suppressing the number on them; France operates Bloctel and restricts telemarketing hours and frequency; Spain requires consent or a prior relationship for marketing calls. CLI validation for international calls presenting domestic numbers is spreading fastest here. See Germany, France, Spain and the UK.
Latin America
Brazil, Mexico and Argentina each run national do-not-call registers, and Brazil has gone furthest by requiring the 0303 prefix for telemarketing. Number formats changed in several countries over the last decade (Mexico removed the mobile "1" after +52 for dialling, Brazil added a ninth mobile digit), so clean your lists against current formats. See Brazil, Mexico and Argentina.
Asia-Pacific, Middle East and Africa
Australia's ACMA enforces the industry code that requires a valid, diallable CLI and lets networks block calls that present invalid or unallocated numbers. Japan's market is concentrated on a few large operators with strict interconnect rules. The UAE and the Philippines regulate telemarketing actively, and South Africa's POPIA governs direct marketing consent. See Australia, Japan, UAE, Philippines and South Africa.
Pre-campaign checklist for a new country
- Confirm which number types you may present to that country, and that you hold them.
- Check whether international calls presenting domestic numbers are blocked or relabelled.
- Identify the do-not-call register and how often you must scrub against it.
- Note permitted calling hours and any frequency limits.
- Check whether automated or prerecorded calls need a specific form of consent.
- Format every number in E.164 and validate a sample against current numbering plans.
- Run a short acceptance test with CLI sampling before scaling up.
Misconceptions we hear often
- "If the route delivers it, it must be allowed." A route can carry a number that the destination regulator prohibits you from presenting. Delivery and legality are separate questions.
- "A local number always improves answer rate." Only if it is recognisable and callable. An unfamiliar local number that goes unanswered on callback quickly gains a poor reputation.
- "Rules only apply to telemarketing." Most CLI presentation rules apply to all calls; telemarketing rules add consent, hours and register requirements on top.
- "Withheld numbers avoid labelling." Many networks and handsets treat withheld calls with the most suspicion of all, and recipients rarely answer them.
When in doubt, present a valid number you hold, in E.164, that the recipient can call back and that reaches you. That single rule keeps you compliant in most markets and gives the best long-term answer rates.
How we keep these summaries current
Our compliance team reviews each country summary at least twice a year and whenever a regulator publishes a change. The "last reviewed" date on each page shows when it was checked. Summaries are written to be practical, not exhaustive, and are not legal advice.
About the author
Priya Natarajan, Compliance Lead
Priya leads customer onboarding, caller-ID authorisation and campaign review. She previously worked on numbering and consumer-protection policy for a European telecoms operator.
Published · Last reviewed