In short. Switching carriers while keeping your number through number portability does not make you any more anonymous: the number remains tied to your identity at the new carrier, and your earlier connection data is still retained by the old one. On the other hand, all your settings vanish — permanent caller ID blocking, call filtering, voicemail options — and have to be set up again by hand.
Information verified on 9 November 2026 on the public pages of Arcep, the CNIL, service-public.fr, Légifrance and cybermalveillance.gouv.fr, as well as on the support pages of Orange, SFR, Bouygues Telecom and Free Mobile. This article provides general information and is not a substitute for advice from a legal professional.
Does keeping your number when switching carriers make you anonymous again?
No. Portability moves a number from one network to another, not from one identity to another. The new carrier opens a contract in your name, with the same supporting documents as a brand-new subscription, and in turn becomes the point of contact for any court orders concerning that number.
This is a common misconception, and it comes from a reasonable intuition: if I leave Orange for Free Mobile, the history held by Orange should no longer concern me. Technically, the routing does indeed change networks. Legally, nothing is erased: carriers are required to retain certain connection and identity data for a period set by the French Postal and Electronic Communications Code, and that obligation does not disappear because you have left.
In other words, a number ported three times in ten years is still a number whose chain of assignment can be reconstructed. Each successive carrier holds the slice of history that concerns it.
Key point: portability is a commercial convenience (no need to notify your entire address book), not an anonymity tool.
What does the recipient of a text message see after a carrier change?
Exactly the same thing as before: your number, in plain sight, just as it appears in their contacts. The routing network shows up nowhere in a received text message.
Nothing in the header of an ordinary text message indicates the sender's carrier. The recipient cannot tell from a message that you have just moved to another provider. That is why portability solves no privacy problem at all: if someone knew your number, they still do, on the same apparent network — yours.
And the caller ID blocking prefix changes nothing in this logic, as we explain in why #31# does not hide a text message: that code acts on how your number is displayed on voice calls, never on a written message.
What about calls?
Here, one detail matters. If you had enabled permanent caller ID blocking for your number in your online account, that option is a service attached to the line at the carrier. It does not travel with the number. After porting, your number is displayed again by default on your calls, until you re-enable the option with your new provider.
This is the most common trap of switching carriers for anyone who valued that discretion: you assume the setting carried over, and the first call you make gives you away.
Which settings need to be redone after porting?
Here is the list of items to go through one by one, ordered by how much damage they cause when forgotten.
| Item | Follows the number? | Where to redo it |
|---|---|---|
| Permanent caller ID blocking (calls) | No | Online account / carrier support |
| Per-call blocking with #31# | Yes (universal network code) | Nothing to do |
| Voicemail greeting and PIN | No | Reset after SIM activation |
| Call and number blocking (carrier service) | No | Online account |
| Unlisted number / directory opt-out | Must be requested again | Sign up with the new carrier |
| Telemarketing opt-out (Bloctel) | Yes, registration applies to the number | Nothing to do, check on bloctel.gouv.fr |
| Reporting to 33700 | Not applicable (one-off service) | — |
| Blocking numbers on the phone itself | Yes (local to the device) | Nothing to do if you keep the handset |
| Dual SIM / secondary eSIM | No, the eSIM must be reinstalled | Carrier app, QR code |
Two rows in this table deserve a comment.
The unlisted number option (keeping your details out of directories and directory enquiry services) is a contract service, not a property of the number. A long-protected number can become publishable again if the option is not requested anew with the new carrier. The right to object still exists, but you have to exercise it.
The eSIM, for its part, is a profile downloaded onto the device. It is not "transferred": the old profile is deactivated and a new one is installed. If you were using a second number to write discreetly — the method described in dual SIM: a secondary number for writing discreetly — check that, in the rush of switching, you have not left the wrong line set as the "default SIM for messages". That is the mistake that sends a text from the very number you want to keep private.
Does the RIO code reveal anything about me?
The RIO (Relevé d'Identité Opérateur, or carrier line identity statement) is a technical identifier for your line, obtained by calling 3179 from the phone in question, a free service regulated by Arcep. Its only purpose is to prove to the new carrier that you really are the holder of the number to be ported.
It does not contain your name in plain text, but it is no harmless secret either: combined with your number, it allows someone to request a port-out. This is precisely the mechanism exploited in SIM swap fraud, where a third party hijacks a line to intercept verification codes sent by text message. Cybermalveillance.gouv.fr lists this type of attack among the threats targeting online accounts.
The practical consequence is simple: treat a RIO code like a password. It has no business appearing in a conversation, a saved email or a shared note. For those who keep sensitive credentials off every device, a paper password notebook stored at home remains the most low-tech solution — provided it is not left lying on a desk.
How can you limit the risk of fraudulent porting?
- Enable a PIN or two-factor authentication on your carrier's online account, where offered.
- For sensitive accounts, prefer a verification method that does not go through SMS: an authenticator app or a physical key. A FIDO2 security key costs about as much as one monthly plan and survives the loss of a line.
- React immediately to an unexplained loss of network: a line that "drops" for no reason while the phone works fine is the first sign of an unrequested port-out.
- Keep the confirmation emails for your genuine request: they pin down the exact date of the operation.
What happens to my old line and its messages?
Porting counts as cancellation of the old contract: you have nothing further to do with the carrier you are leaving, that is the one-stop-shop principle restated by Arcep. But three leftovers survive the departure.
- The old carrier's voicemail. Messages left before the switchover are not transferred. If it holds recordings you want to keep — or erase — you must do so before the porting date. We go into what a voicemail service actually keeps in withheld numbers: what voicemail keeps.
- Itemised bills. They remain accessible for a while in the old online account, then disappear from the interface without the data being deleted on the carrier's side. If an itemised bill serves as evidence in a legal procedure, download it before the account closes.
- Identity and traffic data. These are retained for the statutory periods, regardless of the contract ending. It is this point that makes the idea of a "clean slate through switching carriers" illusory.
On that last point, the CNIL recalls that you have a right of access to this data from every data controller — including a former carrier. A written request, proof of identity, and a reply within one month in principle.
Changing your number or changing carriers: which one really protects you?
The two steps have nothing in common, and that is the question that comes before all the others.
| Goal | Switch carriers (number ported) | Change number |
|---|---|---|
| Pay less | Effective | No effect |
| Stop being reachable by someone | No effect | Effective |
| Hide your number on calls | Must be reconfigured | Must be reconfigured |
| Start over with a number nobody knows | No effect | Effective |
| Keep your contacts and accounts | Seamless | Significant updating work |
If your problem is someone who keeps texting you, portability will not help: your number stays the same, and their messages will keep arriving. The right approach is described in changing your number to escape a harasser, and it starts with preserving evidence, not with cancelling your contract.
If your problem is cost or coverage, portability is exactly what you need — and you can consider it without fear for your privacy, provided you redo the list of settings above.
Does a new carrier change anything about anonymous texts?
Almost nothing, and that is important to understand so as not to fool yourself.
The methods that let you write without revealing your number — an online sending gateway, a secondary number, a dedicated service — rely on a sender different from your own, not on your carrier. They work the same way on Orange, SFR, Bouygues Telecom or Free Mobile. You can indeed send an anonymous text message without your plan provider entering into the equation at all.
Three caveats all the same.
- Receiving messages from short codes. Some SMS verification services go through short codes whose routing depends on agreements between carriers. A message that used to arrive fine may be delayed in the first few hours after porting, while the network routes are updated. Wait before concluding that something is blocked; our troubleshooting page lists the other causes of failure.
- Spam filters. Each carrier applies its own filtering rules. A sending service that used to work may be handled differently on your new network.
- Blocking withheld-number calls. If you had enabled an option to reject calls with no number, it disappears too. The setting to redo, this time on the phone side, is explained in rejecting withheld calls without missing a text.
Good hardware habits at switchover time
Switching carriers is one of the rare moments when you physically handle your line. You might as well make the most of it.
The outgoing SIM card sometimes holds old contacts and text messages saved directly on it, inherited from a previous phone. Before throwing it away, read it: a USB SIM card reader lets you view and erase that content on a computer. Many people discover messages several years old on this occasion.
Then destroy the chip rather than leaving it in a drawer: two snips of the scissors through the gold contacts are enough, and a shredder with a card slot does the job cleanly if you also have old bank cards to dispose of. Also think about the SIM format adapter if you are moving from one phone to another at the same time: a nano-SIM adapter kit saves you from damaging a card tray with the wrong size.
Finally, if you keep an old line running in parallel for a while — a sensible strategy to avoid missing anything during the transition — a basic second phone saves you juggling two SIMs in the same device, and naturally keeps the two numbers separate.
Key takeaways
- Porting preserves both the number and the identity: no anonymising effect whatsoever.
- Permanent caller ID blocking, directory opt-out, call blocking and voicemail are carrier services: they do not follow you and must be requested again.
- The #31# code remains valid everywhere, but applies only to calls, never to text messages.
- The RIO code (3179) deserves the same protection as a password: combined with your number, it is enough to launch a port-out.
- To stop being contacted by someone, it is your number you need to change, not your carrier — and the stop being contacted page sets out the useful steps.
Updated 9 November 2026. The procedures and options described may change: check the terms currently in force on your carrier's support page and on arcep.fr.
Frequently asked questions
Does porting erase my history with my former carrier? No. Cancellation ends the contract, not the statutory obligations to retain identity and connection data. A former carrier remains a possible recipient of a court order covering the period when you were a customer.
Does my withheld number stay withheld after a carrier change? No, if the blocking was permanent and enabled in your online account: the option is tied to the contract. It must be re-enabled with the new carrier. Per-call blocking with #31#, on the other hand, keeps working with no setup.
How long does porting take, and will I be unreachable? The operation takes a few business days, and the actual interruption lasts from minutes to a few hours on switchover day. During that short window, incoming calls and texts may not get through.
Can someone port my number without my knowledge? That is what is known as SIM swap fraud, and it requires knowing your number and your RIO code. Secure your online account, never share your RIO code, and treat any unexplained loss of network as a warning sign.
Do I need to cancel my old plan after porting? No. The porting request automatically cancels the old contract: a second cancellation could, on the contrary, make you lose the number.
