The 04 area code designates fixed phone numbers linked to the South-East of France in the numbering plan managed by ARCEP. This prefix covers the regions of Auvergne-Rhône-Alpes, Provence-Alpes-Côte d’Azur, and Corsica. Following a recent reform, certain sub-prefixes like 04 24 have been detached from this geographical logic to serve a completely different purpose: identifying telemarketing calls.
The 04 24 prefix reserved for telemarketing: what the ARCEP reform has changed
Confusion is common. A call from 04 24 resembles a local call from the South-East, but 04 24 is a national prefix dedicated to telemarketing, with no link to a geographical area. ARCEP has mandated that outgoing commercial calls transit through a series of identifiable prefixes, including 04 24 (alongside 01 62, 02 70, 03 77, 05 68, and 09 48).
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The goal is simple: to allow the recipient to recognize the commercial nature of the call even before answering. Understanding the 04 12 area code for France requires distinguishing these dedicated sub-prefixes from actual geographical codes.
Numbers starting with 04 24 are primarily used by prospecting platforms and automated calling systems capable of generating massive volumes. When a call comes from this prefix, the likelihood that it is a commercial solicitation is very high.
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Prefix filtering on smartphones: settings and applications
Blocking a number afterwards is not enough when calls come from dozens of different numbers sharing the same prefix. Prefix filtering allows for the automatic rejection of all calls starting with 04 24, without manual intervention for each new call.
Setting up blocking on Android and iOS
On Android, most manufacturer overlays (Samsung, Xiaomi, Google Pixel) offer native filtering of calls identified as spam. However, specific prefix blocking requires a third-party application.
On iOS, the “Silence Unknown Callers” feature redirects any call from a number not in the contacts list to voicemail. This setting is radical: it does not target a specific prefix, but cuts off all unidentified calls.
Filtering applications that include ARCEP prefixes
Several call filtering applications now integrate automatic blocking of prefixes reserved for telemarketing, including 04 24. Here are the criteria to check before installing one:
- The database must be regularly updated to include new prefixes imposed by ARCEP, not just numbers reported by the community
- The filtering must work by prefix (04 24, 01 62, etc.) and not just by individual number, otherwise most calls will get through
- The application should not require access to SMS content or the complete contacts list for simple blocking of incoming calls
A well-configured prefix filtering eliminates nearly all telemarketing from 04 24 without affecting legitimate calls from other 04 sub-prefixes.
Bloctel and dedicated prefixes: two complementary systems
Bloctel is the legal device for opposing telemarketing. Registration on this list prohibits professionals from soliciting the registered numbers, even if they use a dedicated prefix like 04 24. The only exception is a pre-existing contractual relationship between the professional and the consumer.
Technical filtering by prefix and Bloctel do not operate on the same level. Bloctel acts upstream, on the sender’s side: companies complying with the law purge their prospecting files. Prefix filtering acts downstream, on the receiver’s side, to block calls from operators who ignore Bloctel.
Combining both approaches offers protection on two levels:
- Bloctel reduces the volume of allowed calls, which decreases the overall pressure on your line
- Prefix filtering intercepts calls that get through despite Bloctel, made by platforms that do not respect the opposition list
- Registration with Bloctel is free and done online, with automatic renewal
Geographical 04 area code: national and international calling format
Aside from the specific case of 04 24, numbers starting with 04 remain classic geographical numbers. The international format is +33 4 followed by the eight digits of the number, omitting the initial zero.
A number displayed as 04 12 XX XX XX corresponds to the South-East area and follows the usual rules: calls are included in the fixed and mobile plans of French operators, with no surcharge. From abroad, the pattern remains the same regardless of the country of origin: country exit code (00 or +), then 33, then 4, followed by the eight digits.
04 numbers and cloud telephony
Companies wishing to have a number starting with 04 without a physical presence in the South-East can obtain this type of line through a cloud telephony operator. The number is then virtually linked to the geographical area while being managed from any location. Intelligent routing allows incoming calls to be redirected to multiple extensions, a voicemail server, or a mobile phone, without the caller noticing any difference.
Number portability is guaranteed by regulation: changing operators does not mean losing your 04 number, whether the line is physical or hosted in the cloud.
The distinction between a geographical 04 and a 04 24 for telemarketing relies solely on the two digits following the prefix. Checking this sub-prefix before returning a missed call helps avoid contacting a prospecting platform, which may trigger a new call in the following hours.