Before you start

Passport, for a prepaid SIM
A French RIB, for most contract tariffs
An unlocked or eSIM-capable handset
A French address, for fibre installation

Step-by-step

1
Buy a prepaid SIM on your passport the day you arrive
Available in phone shops and in tabacs. Identity verification is required but a passport satisfies it. A French number in your first hours unlocks bank verification codes and appointment systems that will otherwise block you.
In personWho: YouDay 1
2
Move to a sans engagement contract once you have a RIB
French no-commitment tariffs are month-to-month and remarkably cheap for large data allowances. There is little reason to take a long commitment unless a subsidised handset genuinely justifies it, and it usually does not.
OnlineWho: You
3
Leave FR-Alert enabled, and learn what the sirens mean
France broadcasts emergency messages to every handset attached to the cells in an affected area through FR-Alert — no app, no subscription. In the Seine valley the alert you are most likely to receive concerns an industrial incident. Separately, the physical warning sirens are tested at noon on the first Wednesday of the month; a real signal is a different, rising and falling pattern and it means go indoors, close windows and ventilation, and listen to the radio rather than going to look.
OnlineWho: YouWeek 1
4
Order fibre as soon as you have an address
Coverage across the métropole is extensive and prices are low. Installation usually takes one to three weeks and may require a technician visit and access to the building's riser.
OnlineWho: You
5
Ask about the building's fibre at the viewing
The timber-framed and listed stock in the old town depends on what the copropriété has agreed to have installed, and heritage constraints on external works are real here. Operator coverage checkers work at street level, so the street can be served while a specific flat is not. If you work from home, make it a viewing question.
OnlineWho: You
6
Keep your number when you switch operators
Request your RIO code by calling 3179 free of charge from the line you want to port, then hand it to the new operator, which runs the switch and terminates the old contract automatically. Never cancel first — you lose the number permanently.
Mobile appWho: You

Documents you’ll need

Passport, for prepaid registration
French RIB, for a contract
Justificatif de domicile, for fibre installation

Things most newcomers don’t know

In this valley the emergency alert on your phone is not a theoretical feature.

FR-Alert pushes warnings to every handset in a defined area using the cell network rather than an app you must install, and the Seine corridor's density of classified industrial sites is exactly the situation it exists for. The 2019 Lubrizol fire is within living memory for everyone here and shaped how the state now communicates during an industrial event. People who switch off unfamiliar alert categories while setting up a new phone are disabling the fastest channel designed to reach them.

Source: ministère de l'Intérieur — FR-Alert

The monthly siren test is at noon on the first Wednesday, and a real alert sounds different.

France tests its national warning sirens on the first Wednesday of each month, and residents near classified sites hear them regularly enough to stop noticing. The real signal is a modulated rising and falling tone repeated in cycles, and the correct response is counter-intuitive: go inside, close windows and stop ventilation, do not go to collect children from school, and do not phone the emergency services for information. Learning that once, calmly, is a five-minute investment.

Source: ministère de l'Intérieur

French mobile is cheap in a way that surprises almost every arrival.

The entry of a disruptive fourth operator in 2012 triggered a price war whose effects never reversed, and France now has some of the lowest mobile tariffs in western Europe. Large-data plans with no commitment cost a fraction of the UK, Irish or German equivalent. Anyone paying a high monthly mobile bill in France has simply not looked at what is available.

Source: Arcep

The RIO code is how you keep your number, and you request it from the line itself.

Call 3179 free of charge from the phone you want to port and a voice server reads you a RIO code and sends it by SMS. Give that to the new operator; they execute the switch and close the old contract automatically. Cancelling the old service first loses the number for good, and very few newcomers know the number exists — it is the most common self-inflicted telecom mistake in France.

Source: Arcep

Common mistakes to avoid

Disabling government emergency alerts while setting up a new handset.
Hearing a real siren and going outside to look rather than going in and closing up.
Signing a two-year commitment when no-commitment tariffs are cheap and switchable.
Cancelling your old service before requesting the RIO code and losing the number.
Assuming fibre is available in a listed timber-framed building because the street is covered.

Some of this may be out of date. Spotted something inaccurate? Help us keep it right for the next newcomer.