The area code 04 corresponds to the fixed lines in the southeast region of metropolitan France. A number starting with 04 12 falls within this geographical division, but its precise meaning and the uses that arise from it deserve some technical clarifications.
Authentication of fixed calls: what has changed for numbers starting with 04
Since October 3, 2024, a mechanism for authentication of fixed numbers has come into effect in France. The goal: to limit telephone identity theft on outgoing calls. In practical terms, an operator routing a call displayed as 04 must verify that the number presented is indeed assigned to the actual caller.
This measure directly affects numbers starting with 04 12. Before this system, it was technically simple for a third party to display a local number starting with 04 on the recipient’s screen without being the actual holder. This practice fueled abusive telemarketing campaigns and scam attempts reported by numerous users.
For an individual receiving a call from a number starting with the area code 04 12, this authentication enhances the reliability of identification. A number displayed as 04 12 is now more likely to correspond to its true holder than before October 2024.
French numbering plan: locating an area code 04 12
The French telephone numbering plan divides the metropolitan territory into five zones, each identified by a first digit after the 0. Zone 4 covers the southeast: Corsica, Auvergne-Rhône-Alpes, Provence-Alpes-Côte d’Azur, and part of Occitanie (formerly the Languedoc-Roussillon region).
The two digits following 04 (here, 12) correspond to a block assigned by Arcep to an operator. This block does not always designate a specific city or department. It identifies the operator that obtained the range of numbers, and this operator can then distribute them to subscribers located throughout zone 4.
Geographic or virtual number
Since January 1, 2023, the obligation for geographic localization for fixed numbers has been removed. A number starting with 04 12 can therefore be assigned to a company whose premises are located in Lyon, Marseille, or even outside the southeast region, via a cloud-hosted telephone system.
This evolution explains why some calls from 04 12 come from companies that have no physical presence in the southeast. The number remains technically linked to zone 4, but its user can operate from anywhere in the territory.
Local presence dialing: why companies use a number starting with 04
Local presence dialing is a professional telephony technique that involves displaying a local number during an outgoing call. The goal is to improve the answer rate: an individual in the Rhône-Alpes region is more likely to answer a call displayed as 04 than a call displayed as 01 or 09.
Several business telephony solutions offer this feature. However, the legal framework imposes a clear constraint: the number presented must be legitimately assigned to the caller. A company based in Paris cannot randomly display a 04 12. It must have a 04 12 number that has been legitimately assigned to it by an operator.
Distinguishing a professional call from a scam
Despite the strengthening of authentication, reports of fraudulent calls from numbers starting with 04 12 continue to circulate. A few reflexes can help sort them out:
- A legitimate call from a company with which you have a contractual link will often be identifiable via your customer history or your online account.
- A call followed by a voicemail asking you to return a premium-rate number (starting with 08) is a classic scam signal. Numbers starting with 04 are never premium-rate themselves, but they can be used as bait.
- A number that calls multiple times without leaving a message, then hangs up immediately, often corresponds to a prospecting automated system testing the validity of your line.
Portability and retention of a number starting with 04 12
The portability of fixed numbers works the same way for a 04 12 as for any other French geographic number. By changing operators, the holder can keep their number using the RIO code (Operator Identity Statement), obtained by calling 3179 from the concerned line.
For a company, retaining a number starting with 04 12 during a migration to a cloud telephony operator represents a direct commercial challenge. Clients and suppliers know this number, and changing it results in a loss of reachability during the transition.
The portability procedure generally takes a few business days. The receiving operator (the one to which you are migrating) handles all the steps with the donor operator. No prolonged service interruption is supposed to occur.
Calling a 04 12 from abroad: international format
From abroad, a number starting with 04 12 XX XX XX is dialed in the international format +33 4 12 XX XX XX. The initial 0 disappears, replaced by the country code for France (+33). This rule applies to all French fixed numbers, regardless of their area code.
The call is charged as an international call to France, unless your mobile plan includes calls to French landlines. From a country in the European Union, roaming fees regulated by European legislation may apply if you call from your own French mobile line while traveling.
A number starting with 04 12 remains a non-premium number. The caller only pays the cost of a call to a metropolitan landline, included in most current French telephone plans. This feature distinguishes it from special numbers starting with 08, whose pricing varies according to the type of service.
