Today, Arcep is publishing a draft decision for public consultation, amending the framework for assigning and utilising numbering resources. This draft decision includes a range of changes to applicable rules, in particular with a view to giving operators tools to complete the caller ID authentication mechanism and prevent number spoofing. It also brings changes to the numbering plan to factor in the new provisions of the Law of 30 June 2025 to combat public aid fraud.
Strengthening protective measures to curb caller ID spoofing
The Law of 24 July 2020 on supervising telemarketing and combatting fraudulent calls[1] provides for the implementation by operators of a caller ID authentication mechanism, whose technical specifications were designed by French telcos. This mechanism, which is currently being used by virtually every operator in France, requires that information for identifying a call’s originating operator be provided for every call. This traceability, combined with operators’ cooperation, creates the ability to identify the origin of fraudulent calls, after the fact.
Arcep has nevertheless received more than 10,000 reports on its “J’alerte l’Arcep” user reporting platform since January 2025 that have been classified under number spoofing, proving that scam call perpetrators have found ways to circumvent the authentication obligation and spoof telephone numbers, especially mobile ones. Even if it is often short-lived, this spoofing is a source of legitimate concern for the subscribers whose number has been spoofed; and they are regularly contacted by people who are upset about having been the target of the calls.
In the draft decision being published for public consultation, Arcep proposes taking action on three fronts:
- Display “99 99 99 99 99” when an international call using a French mobile number could not be authenticated. A very large number of scam calls using a spoofed mobile number are made from abroad to people in France without being filtered, due to French operators’ inability to distinguish legitimate calls being made by French subscribers who are travelling abroad (aka roaming). To ensure that legitimate calls from roaming French customers can reach their destination, while also limiting the risks of number spoofing in cases where French operators are unable to guarantee the authenticity of the caller ID being displayed, in accordance with the powers entrusted to it by the legislature, Arcep sets forth the conditions under which operators can derogate from the obligation to interrupt incoming calls to their international interconnections displaying a mobile number, by requiring them in these instances to replace the caller ID number with a fixed value (“99 99 99 99 99”). This will indicate to the call’s recipient that the displayed number had to be replaced, in the absence of a mechanism enabling the authentication of that number.
- Recommend that operators display “99 99 99 99 99” in those instances where technical restrictions prevent them from relaying caller ID authentication information when routing the call. In some situations, notably due to the limitations of certain equipment that is incapable of rerouting calls according to technical standards, operators are unable to preserve caller ID authentication data. Because these weaknesses can be exploited by experienced fraudsters, Arcep recommends that in these instances as well, this same fixed value (“99 99 99 99 99”) be displayed to avoid potentially legitimate calls from being interrupted by the call recipients’ operators, while also reducing the risks of spoofing.
- Clarify the obligation imposed on call origination operators to verify caller ID numbers used by their customers. The number authentication mechanism relies on a “chain of trust” between operators. It is based on verification performed by the operator on whose network the call originates. The operator verifies that its customer is duly authorised to use the number it wants as their caller ID. To support this systematic verification, Arcep plans to require operators to define the list of numbers that the customer can use as their caller ID in that customer’s service contract, and to restrict the numbers that the customer can use when calling to only those numbers on the list.
Create a category of numbers for calls and messages that serve a general interest objective
Article 16 of the Law to combat public aid fraud[2] requests that Arcep define numbers “dedicated to calls and messages serving a general interest objective” made by automated systems, which can only be assigned to the organisations included on a list set by joint order of the ministers responsible for consumer affairs and for electronic communications. To this end, Arcep is creating a number category for calls and messages serving a general interest objective that are made by automated call systems, which can be assigned to these organisations designated by the ministerial order, and defines the conditions for their use.
Increase the efficiency of overseas number management to avoid a shortages and satisfy businesses’ growing needs
Requests for numbering resources are on the rise, particularly to meet the needs of new use cases. Certain categories of resources allocated under the numbering plan for different overseas territories are now facing shortages. To satisfy the needs of operators and their subscribers, Arcep is proposing a series of measures designed to achieve more efficient management of these numbering resources. Arcep will also assign new ranges of numbers to these territories.
Lastly, Arcep is also proposing to amend certain rules, notably to increase consumer protection. As a result, Arcep is proposing both to prohibit the display of heavily surcharged short numbers as the caller ID, and to automatically freeze a phone number when it is cancelled by an operator, for instance following the technical switchoff of a copper network access line, so that the user in question has the ability to recover their cancelled number before it is reassigned to another user. These changes come in response to requests that operators have made to Arcep, and to user reports submitted to the “J’alerte l’Arcep” site.
Arcep invites all of the affected stakeholders (operators, consumer associations, publishers, individuals) to share their views, either directly or through their representatives, on this draft decision. Contributions must be received by 26 September 2025.
Associated document
To find out more :
- Le grand dossier “La numérotation” (“Numbering” in the Key issues section) of the Arcep website (in French): main laws and regulations, history of Arcep decisions, number portability and directory assistance services