--- title: "International CLI for Call Center Traffic: Carrier Guide" description: "International CLI for call center traffic: 6 checks to avoid blocked calls and ASR drops. See what Switzerland and Belgium require before you route." image: https://www.virtual-call.net/hubfs/AI-Generated%20Media/Images/Blue%20Network%20Gate%20Filtering%20Voice%20Calls.png --- [Skip to content](https://www.virtual-call.net/blog/international-cli-call-center-traffic#main-content) - [Become a partner](https://www.virtual-call.net/become-a-partner) - [My Login](https://my.virtual-call.net) - [Support](https://support.virtual-call.com) [![Virtual-Call your Communication Service Provider](https://www.virtual-call.net/hs-fs/hubfs/VC%20Logo/New/vcall_logo_transparent_white_840x252.png?width=840&height=252&name=vcall_logo_transparent_white_840x252.png) ![Virtual-Call your Communication Service Provider](https://www.virtual-call.net/hs-fs/hubfs/VC%20Logo/New/vcall_logo_400x120.jpg?width=400&height=120&name=vcall_logo_400x120.jpg)](https://www.virtual-call.net?hsLang=en) - [English](https://www.virtual-call.net/blog/international-cli-call-center-traffic) - [Deutsch](https://www.virtual-call.net/de/blog/cli-internationaler-call-center-verkehr) - [Português - Brasil](https://www.virtual-call.net/pt-br/blog/cli-internacional-call-center) - [Home](https://www.virtual-call.net) - Cloud Products - [Cloud PBX](https://www.virtual-call.com/cloud-pbx) - [SIP Trunk](https://www.virtual-call.com/sip-trunking) - [MS Teams Direct Routing](https://www.virtual-call.com/microsoft-teams-direct-routing) - [Wholesale](https://www.virtual-call.com/wholesale) - [About us](https://www.virtual-call.net/about-us) - [Blog](https://www.virtual-call.net/blog) ###### 14 min read # International CLI for call center traffic: check before you activate By: [Otto Kolbe](https://www.virtual-call.net/blog/author/otto-kolbe) on Oct 8, 2026, 12:00:02 AM [international call blocking CLI](https://www.virtual-call.net/blog/tag/international-call-blocking-cli) [CLI rules by country](https://www.virtual-call.net/blog/tag/cli-rules-by-country) [call center VoIP route](https://www.virtual-call.net/blog/tag/call-center-voip-route) [caller ID spoofing rules](https://www.virtual-call.net/blog/tag/caller-id-spoofing-rules) ![Featured Image](https://www.virtual-call.net/hubfs/AI-Generated%20Media/Images/Blue%20Network%20Gate%20Filtering%20Voice%20Calls.png) Your ASR drops, the campaign has not changed, and the upstream route reports filtering. You review the route and the dialer, and the problem stays. The cause may be a detail that can get checked too late: the number the called party sees. International CLI for call center traffic must be permitted in the destination, proven by the customer, and compatible with the route. Otherwise, the call can be blocked or the number masked. Below are six checks that make activation predictable, and the reason a Swiss number can disappear on the way. (CLI, Calling Line Identification, is the number the called party sees.) *This content is informational and does not constitute legal advice. The rules cited were verified in October 2026 and change frequently. Confirm the regulation in force with your route supplier and, where needed, with specialist legal counsel.*   International CLI for call center traffic: check before you activate 4:57   ### Content sections [1. International CLI for call center traffic: the rule that causes most blocking](https://www.virtual-call.net/blog/international-cli-call-center-traffic#international-cli-for-call-center-traffic-the-rule) [2. Destinations that restrict call center traffic itself](https://www.virtual-call.net/blog/international-cli-call-center-traffic#destinations-that-restrict-call-center-traffic-its) [3. The right route for the traffic type](https://www.virtual-call.net/blog/international-cli-call-center-traffic#the-right-route-for-the-traffic-type) [4. What the carrier should require from the end customer](https://www.virtual-call.net/blog/international-cli-call-center-traffic#what-the-carrier-should-require-from-the-end-custo) [5. Checklist: six points before activating a destination](https://www.virtual-call.net/blog/international-cli-call-center-traffic#checklist-six-points-before-activating-a-destinati) [6. Minimum documentation: ownership and audit trail](https://www.virtual-call.net/blog/international-cli-call-center-traffic#minimum-documentation-ownership-and-audit-trail) [7. Signs that a route is in trouble](https://www.virtual-call.net/blog/international-cli-call-center-traffic#signs-that-a-route-is-in-trouble) [8. Good dialing practices](https://www.virtual-call.net/blog/international-cli-call-center-traffic#good-dialing-practices) [9. When to seek technical support](https://www.virtual-call.net/blog/international-cli-call-center-traffic#when-to-seek-technical-support) [10. Frequently asked questions](https://www.virtual-call.net/blog/international-cli-call-center-traffic#frequently-asked-questions) [11. Conclusion](https://www.virtual-call.net/blog/international-cli-call-center-traffic#conclusion)   ## International CLI for call center traffic: the rule that causes most blocking Several countries have adopted measures against international calls that present a national number as CLI. The logic: a call arriving from abroad with a local number has a high probability of being falsified. How the measure is applied varies by country: marking, number removal, masking, or blocking. ### 1. Switzerland The technical and administrative regulation of the Federal Office of Communications (OFCOM/BAKOM) on calling line identification requires transit providers to mark calls arriving from abroad that carry a Swiss number. The marking must include the name of the provider that performed the identification. If the call cannot be identified for technical reasons, the transit provider must remove the number. On that basis, the terminating provider may suppress the displayed number or block the call. The requirement applies to landline numbers from 1 January 2026 and to mobile numbers from 1 July 2026. ### 2. Belgium The Royal Decree of 12 May 2024 requires operators to block international calls that present a Belgian number (geographic, non-geographic, or mobile) as CLI. The obligation applies from 1 September 2024 for landline numbers and from 1 December 2024 for mobile numbers. There are exceptions for bona fide applications, such as cloud-based call centers and customer support services, and they apply only to Belgian geographic numbers. In these cases, the company must register the numbers with its operator. The operators involved must keep the calls under their own control (for example, through a VPN or direct connection) and formalize the exception in a written agreement that lists the numbers. In June 2026, the BIPT published guidance on which operator is responsible for blocking and how to treat transit traffic routed through other countries. In addition, Belgian numbering rules prevent non-geographic numbers, such as the 078 range, from being used as CLI and require the CLI to match the number assigned to the end user. ### 3. Other destinations The United Kingdom, France, Italy, and Spain also have their own CLI rules, and they change frequently. The table summarizes the situation at the verification date. It is a starting point and does not replace validation per destination. | Destination | What to check | | --- | --- | | United Kingdom | International calls presenting a UK number as a presentation number must be blocked or treated. The +447 mobile exception is conditional (NICC ND1447, since 29 Jan 2025). | | France | Geographic and multi-purpose numbers cannot be CLI without authentication. Since 1 Jan 2026, a French mobile CLI that fails authentication may be masked. | | Italy | AGCOM Resolution 106/25/CONS: phased blocking of spoofed Italian CLI. Landline from 19 Aug 2025, mobile from 19 Nov 2025. | | Spain | Since 7 Jun 2025, Spanish mobile numbers are restricted as CLI on commercial calls. From Oct 2026, commercial calls require the 400 range. | A starting point for per-destination validation, not a substitute for it. Source: provider reference (CM.com). Rules change often.   ### 4. Outside Europe: Brazil as an example Brazil shows how call authentication is becoming mandatory outside Europe. Anatel's General Telecommunications Services Regulation (RGST), approved by Resolution No. 777/2025, provides for call authentication. The implementation uses the STIR/SHAKEN protocols, and ABR Telecom operates the Origem Verificada service. Anatel has extended part of the regulation's deadlines. Since November 2025, “large callers” (more than 500,000 calls per month with one provider) must authenticate all their calls or risk blocking. For a broader regulatory context, see our [international VoIP provider guide](https://www.virtual-call.net/blog/choosing-your-ideal-international-voip-provider?hsLang=en). This article covers what changes when the call crosses a border.   ## Destinations that restrict call center traffic itself In some destinations, the issue is not only the CLI but also the traffic type. Route supplier policies may restrict call center calls, aggressive dialing, or the use of CLI from the destination country itself. Some suppliers do not accept these profiles on routes to China, Australia, Hong Kong, and New Zealand. For China, the restriction may also include wholesale traffic. Sending traffic outside the agreed conditions can result in a rate increase or a block on the destination. These restrictions are not identical across suppliers. Confirm in writing which profiles your route accepts before sending calls in volume.   ## The right route for the traffic type A route designed for long conversations does not tolerate a dialer pattern: many attempts, short calls, and low ACD (Average Call Duration). That is why routes are separated by profile. In Virtual-Call's wholesale VoIP termination, the Premium and EEA Premium routes require a minimum ASR of 50% and an ACD of 1.5 minutes. The EEA Premium route works only with a valid caller ID from an EEA country. The Call Center route, built for short-duration outbound campaigns, works with a minimum ASR of 45% and an ACD of 20 seconds. The same page lists destination restrictions: there are no call center routes for the USA, China, and for the UK, the route is available only with a caller ID from outside the UK. The domestic CLI routes with local ANI are designed for conversational traffic and are not suitable for call center traffic. If your traffic is dialer traffic, use the route designed for it. Campaign traffic on a premium route tends to be filtered.   ## What the carrier should require from the end customer The carrier answers for the traffic it forwards. Before activating a destination for a call center customer, record: - The traffic profile (collections, sales, support, and surveys), the expected volume, and the destinations; - Which CLIs the customer intends to present and proof of the right to use them; - The contractual commitment not to manipulate CLI and to respect the agreed dialing pace; - Who, on the customer side, is responsible for number-reputation incidents. This reduces the carrier's exposure to the upstream route and speeds up the response when a question comes in.   ## Checklist: six points before activating a destination | # | Check | Why it matters | | --- | --- | --- | | 1 | Do the destination and the route supplier accept call center traffic? | Some restrict or prohibit this use. | | 2 | Which CLI is permitted: origin country, international or destination country? | Determines whether the call passes and how it is rated. | | 3 | Does the customer prove the right to use the presented number? | Reduces the risk of blocking and reputation problems. | | 4 | Is a document required (LOA, number registration, operator agreement)? | In stricter destinations, it is the proof of the right to use. | | 5 | Does the route match the dialer profile? | Campaign traffic on a Premium route tends to be filtered. | | 6 | Are ASR, ACD, and blocking monitored per customer and destination from day one? | A sharp drop is often the first sign of filtering. | Checklist for carriers routing call center traffic abroad. Source: Virtual-Call.   [Download the PDF checklist](https://www.virtual-call.net/hubfs/blog/Checklist%20CLI%20Internacional/checklist-en-international-cli-call-center.pdf?hsLang=en) to use on every destination activation.     ## Minimum documentation: ownership and audit trail In stricter destinations, using a number requires proof that it belongs to the customer or that the customer is authorized to use it. The LOA (Letter of Authorization) is one of the documents used to prove that right. Keep, at a minimum: - Proof of ownership or the LOA for each CLI; - The list of active CLIs per customer, route, and destination; - The change history (who changed the CLI, when, and why).   ## Signs that a route is in trouble Before a full block, a route usually shows signals: - ASR drops without a change in list or campaign; - ACD falls suddenly; - PDD (Post Dial Delay, the time between dialing and ringing) increases; - answered calls without audio; - complaints from call recipients. **Avoid changing the CLI after every drop.** Rotating numbers without criteria tends to worsen reputation. It is safer to keep a few documented numbers with consistent behavior.   ## Good dialing practices - Adjust the dialer pace to the destination. Aggressive pacing is a common filter trigger. - Limit attempts per contact. - Segment by country and local time. - Define who can create, change, and retire a CLI. A CLI without an owner becomes a risk.   ## When to seek technical support An operation in one or two known destinations is usually handled with the checklist. The situation changes with several countries, different CLI rules, and the need to prove compliance. In those cases, a voice termination supplier with direct carrier connections and continuous monitoring shortens the path between “the route dropped” and “we know why”. Virtual-Call serves established carriers with [wholesale VoIP termination](https://www.virtual-call.com/wholesale/voip-termination) and 24/7 SIP monitoring. ## Frequently asked questions 1\. What is CLI on an international call? It is the calling line identification, the number displayed to the person receiving the call. Carriers and regulators use it to validate the origin and, in some cases, classify the tariff. 2\. Why is an international call center call blocked? Often because of a combination of a CLI not authorized for that destination, a route unsuited to the dialer pattern, and country-specific rules. 3\. Can I present a number from the destination country as CLI on calls arriving from abroad? It depends on the country. Switzerland and Belgium, for example, have rules that can lead to blocking or removal of the number on calls arriving from abroad, with conditional exceptions. Confirm in writing with your route supplier before activating. 4\. What is an LOA for CLI? It is a letter of authorization that proves the right to use a given number as CLI. 5\. What ASR and ACD should I expect on a call center route? It depends on the route and the contract. On Virtual-Call's call center route, the minimums are an ASR of 45% and an ACD of 20 seconds.   ## Conclusion Activating a destination for call center traffic requires validating the country's policy, proving the right to use the CLI, and using the right route for the dialer profile. With this process, the carrier reduces blocking, protects the reputation of the route, and gains predictability. **Does your carrier forward call center traffic abroad? Talk to the [Virtual-Call team](https://www.virtual-call.com/about-us/contact) and share your destinations, traffic profile, and estimated volume so we can validate the route.** Our wholesale services are available to established carriers and VoIP operators.   We connect you to the world! **🌍**     Sources - BAKOM/OFCOM (Switzerland): [Identification of the calling line](https://www.bakom.admin.ch/en/identification-of-the-calling-line) - BIPT (Belgium): [Royal Decree on spoofing](https://www.bipt.be/operators/spoofing-royal-decree) - CM.com (provider reference: United Kingdom, France, Italy, Spain, and call center restrictions): [Local regulations](https://knowledgecenter.cm.com/knowledge-center/communications-platform/voice/regulations/local-regulations) - Anatel (Brazil): [Resolution No. 777 of 28 April 2025](https://www.in.gov.br/en/web/dou/-/resolucao-anatel-n-777-de-28-de-abril-de-2025-626983026) - Virtual-Call: [Wholesale VoIP termination](https://www.virtual-call.com/wholesale/voip-termination) - [Tweet](https://twitter.com/share) ##### About us About us Virtual-Call GmbH is your partner in communication services. 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