Area Code 1 – Île-de-France

Geographic Coverage and Administrative Jurisdiction

The French national numbering plan, administered by the Autorité de Régulation des Communications Électroniques et des Postes (ARCEP), allocates the geographic prefix 01 to the Île-de-France region. This area encompasses the capital city of Paris and its surrounding administrative departments, including Hauts-de-Seine (92), Seine-Saint-Denis (93), Val-de-Marne (94), and the wider Petite and Grande Couronne zones. The prefix serves a population of over 12 million and hosts the headquarters of major corporations, government institutions, and international organizations.

Dialing Formats and Number Structure

French fixed-line numbers in the 01 zone consist of ten digits in the national format, always beginning with 01. The structure is: 0X XX XX XX XX, where the first two digits after the leading zero represent the geographic area. For example, a Paris number might be formatted as 01 42 68 53 00.

When dialing from abroad, callers must omit the leading zero and use the international prefix, followed by the country code +33. The same Paris number would be dialed as +33 1 42 68 53 00. Note that the space after the country code is often omitted in written form, resulting in +33142685300.

Local and International Caller Instructions

• Domestic calls within France: Always dial the full 10-digit number, including the leading 0. For example, to call a Paris number from Lyon, dial 01 42 68 53 00.
• International calls to France: Replace the leading 0 with the country code. From the United States, dial 011 33 1 42 68 53 00; from the United Kingdom, dial 00 33 1 42 68 53 00.
• Calls from mobile phones: Mobile users in France must also dial the full 10-digit number, as the leading 0 is part of the national dialing plan.

Overlay and Numbering Evolution

As of 2023, the 01 prefix does not have an overlay code; it remains exclusive to the Île-de-France region. However, ARCEP has implemented number portability, allowing subscribers to retain their 01 numbers when moving within the same geographic area or even when switching to a VoIP provider. This means that a number starting with 01 does not guarantee the caller's physical location, as it may be routed via IP networks.

Practical Examples

To illustrate, the Eiffel Tower's main switchboard is reachable at 01 44 11 23 23 (national) or +33 1 44 11 23 23 (international). The Louvre Museum uses 01 40 20 50 50 domestically, which becomes +33 1 40 20 50 50 for callers outside France.