Sophie
11 November 2026 · 12 min read
You send a text to your cousin who settled in Portugal, to a colleague who left to work in Dubai, to a friend who moved back to Senegal. The message goes out, no error, sometimes even a delivery receipt. And yet: total silence for months. When a contact abroad gives up their line, the local carrier takes the number back and puts it back into circulation after a few months. So your text is still being delivered — to the new person who inherited the number. Technically, everything works: there is nothing to report, so nothing is reported to you.
Updated 11 November 2026.
Why does my text send without an error if the number is no longer the right one?
Because the number still exists. It hasn't been deleted: it has simply changed owner. As far as the network is concerned, a number assigned to an active subscriber is a valid number, full stop — the identity behind it plays no part in routing.
That is the fundamental difference with the cases where a text really does fail:
| Situation | What the network does | What you see |
|---|---|---|
| Non-existent number (unknown prefix, wrong length) | Rejected at the entry point of the destination network | "Not delivered" error, sometimes immediately |
| Line cancelled, number in quarantine | Rejection or silent absorption | Often nothing at all |
| Number reassigned to a new subscriber | Normal delivery | Nothing — message "sent", even "delivered" |
| Phone switched off or out of coverage | Queued in the SMSC | "Sent", delayed delivery |
The third case is the most treacherous. It is the only one where the lack of a reply has no technical explanation: the message did arrive, it just landed with someone who doesn't know you and who, in 90% of cases, will never reply.
If you have doubts about how reliable that little "Delivered" label in your app really is, we have broken down what it actually measures — and what it doesn't — in our guide to delivery receipts for international texts.
How long does a number stay "frozen" before being reassigned?
It depends entirely on the country and the carrier, and the timescales are far shorter than you might imagine: often a few months, sometimes a few weeks on prepaid plans.
In France, the framework is set by the numbering plan of Arcep (the French electronic communications regulator), which requires carriers to observe a quarantine period before any mobile number is reassigned — enough time for residual calls and messages to die out. Other countries apply their own national rules, within the general framework of recommendation E.164 from the International Telecommunication Union, which says nothing about quarantine duration: that is a purely national decision. The French rules are published by Arcep.
Three factors shorten that period considerably abroad:
- Number scarcity. A country whose mobile ranges are filling up recycles faster. Markets where multi-SIM use is widespread (West Africa, Southeast Asia, Latin America) burn through huge quantities of numbers.
- Contract-free prepaid. An inactive prepaid SIM is deactivated after a period of inactivity set by the carrier — sometimes three months with no top-up and no use. The number then goes back into the commercial pool.
- Heavily discounted offers. Lines opened for a promotion and abandoned three months later feed a fast recycling cycle.
The upshot: a number jotted down in your contacts two years ago and never used since has a far from negligible chance of belonging to somebody else. And the hungrier a country is for numbers, the higher that chance.
Key point: the absence of an error message proves nothing. It only proves that the number you dialled is currently assigned to an active subscriber.
How can I tell whether my contact has changed numbers?
There is no public service that lets you ask "does this number still belong to X?". Reverse directories don't cover foreign mobiles, and the commercial databases that claim to do so are outdated at best. So the diagnosis has to be made by cross-checking.
The warning signs
- Long, complete silence, when the person used to reply. A contact who no longer answers on any channel has often changed lines.
- A vanished profile picture on the messaging apps tied to the number. When a messaging app linked to the number suddenly shows an empty profile, an unfamiliar avatar or a recent sign-up date, that is the classic sign of a number picked up by a new subscriber. We explain this mechanism in our article on contacts who only use WhatsApp.
- A terse reply from a stranger along the lines of "wrong number": that is direct confirmation.
- A foreign-sounding ringtone when you call, with a recorded message in a language your contact doesn't speak.
Verifying in practice
- Go through another channel. Email, a message on social media, a mutual friend. It is the only reliable method: you are asking the person for the number, not the network.
- Try a short call. Hearing a voice settles the question in ten seconds, where ten texts settle nothing. If the country's network drops you into voicemail, listen to the greeting: a generic carrier answering machine, in the local language, is a bad sign.
- Check the format before blaming the number. A contact saved with a leftover 0 after the country code, or with the code missing altogether, fails for a completely different reason — that is the subject of our guide to the international format of a foreign number.
- Look at the date of the last successful exchange. If it is more than a year old, treat the number by default as "needs reconfirming" before you send anything sensitive to it.
For contacts whose phone line is your only way in — distant family, professional contacts — keeping an up-to-date paper list in a small contacts notebook remains the most robust method: it survives losing your phone, switching systems and syncs that wipe half your address book.
What might a stranger end up receiving from me?
That is the real question, and it is rarely asked. A text sent to a recycled number is not a lost message: it is a message read by a third party.
What goes out without you giving it a thought:
- Family or medical information ("surgery pushed back to the 12th", "results aren't good"), no longer protected by anything at all.
- An address, an arrival time, a flight number. A message like "I land Tuesday at 2pm, the flat is empty until Saturday" has real value for anyone looking to misuse it.
- Verification codes. If you have listed a relative's number as a backup contact on an online service, the code now arrives at the stranger's phone. That is exactly the mechanism behind account takeovers.
- Photos by MMS, which go into the same conversation with no extra safeguard.
The practical rule fits in one sentence: anything you wouldn't write on a postcard should not be sent to a number last confirmed more than a year ago. And if the message concerns an administrative process, a bank or someone's identity, it should go through a channel where you can recognise the person you are talking to.
Note the reverse case too, because it happens: you receive personal texts meant for the previous holder of your number. You are under no obligation to reply, but a simple "this number has a new owner" is helpful and stops the series dead.
Why is the problem far more common abroad than in France?
Because three factors stack up, and none of them works in your favour.
Line mobility. Someone who settles in another country opens a local line, uses it for a year, comes home, and abandons the SIM card without cancelling anything. This scenario is extremely common among expats, students and seasonal workers. The number automatically drops back into the carrier's pool. We covered the flip side — what happens to your own French texts when you put in a local SIM — in the article on using a local SIM abroad.
No visible portability. In France, the number follows the subscriber when they switch carriers, and you never notice a thing. Abroad, portability exists in most countries but not everywhere, and above all: nothing tells you, as the sender, whether the number has been ported, cancelled or reassigned. We cover this in detail in our guide to texting a ported number.
The weight of prepaid. In many countries, the majority of mobile lines are prepaid: no contract, no direct debit, no commitment. A prepaid line switches itself off. It is the quietest form of cancellation there is — and therefore the one most likely to lead to fast recycling.
Add to that numbering plan overhauls, where it is the number itself that changes shape: we documented that scenario in the country changed its numbers.
How can I avoid writing to an old number?
There is no magic fix, but a bit of address book hygiene solves 90% of cases.
Keep a dated address book
- Add the year of confirmation to the contact card. A simple "(confirmed 2026)" in the notes field is enough to tell at a glance whether the number can be trusted.
- Store a second channel for every contact abroad: email, a messaging handle, a relative's number. That is your fallback route when the line goes down.
- Back up your contacts somewhere other than the phone. A contacts export kept on an encrypted USB stick or in a separate file saves you from rebuilding a list from memory — the classic way an expired number resurfaces.
- Clear it out once a year. Duplicate entries, numbers without a country code and lines unused for three years are the leading sources of error.
When you hit send
- Reread the country code shown in the conversation, not just the contact's name. A code that no longer matches where the person lives is a strong signal.
- Start with a neutral message whenever there is doubt: "Hi, is this still you?" costs nothing and prevents an information leak.
- Don't fire off fifteen messages with no reply. Past two or three, the network is no longer the problem.
For frequent travellers juggling contacts in several countries, a dual-SIM phone with an eSIM slot makes life considerably easier: it lets you keep your French line active — and therefore reachable — while using a local line. We go into this in our article on dual SIM abroad. And if you are away for a long time, a portable solar charger stops your main line going dead for want of battery, which is the other way of becoming unreachable.
What if you are the one changing numbers?
The symmetry is worth keeping in mind. Before giving up a line, warn your contacts with a group message, update any services that use the number as a verification method, and ideally keep the line active for a few weeks alongside the new one. A prepaid SIM with a small balance kept alive for two or three months costs little and prevents important messages from vanishing into thin air — or landing with a stranger.
If you need to tell a lot of people at once, you can do it from our send texts to multiple contacts service, or simply send a text from the home page without installing anything.
Frequently asked questions
My text says "delivered" but my contact says they got nothing: who's wrong?
Neither of you. "Delivered" means a handset acknowledged receipt of the message on the destination network — not that it was your contact's handset. If the number has been reassigned, the receipt is perfectly accurate and the message perfectly lost.
Can you find out who a foreign number belongs to?
No, not reliably or legally as a private individual. Reverse directories don't cover mobiles, and commercial databases just recycle old data. The only solid check is to reach the person through another channel.
How long is a mobile number unusable after a line is cancelled?
A quarantine period is required before any reassignment, but its length is set country by country. In France it falls under the Arcep (French electronic communications regulator) numbering plan; abroad it can drop to a few months, or even less on inactive prepaid plans.
Can a verification code sent to an old number be recovered?
No. Once the text is delivered, it is read by the line's current holder. The only remedy is to remove the obsolete number from all your accounts and change the verification method — right away, not "when you get round to it".
Should I delete a contact whose number is doubtful?
Better to keep it but label it clearly ("old number — do not use"). Deleting the entry loses the history, which can sometimes help you track the person down; leaving it untouched guarantees that one day a message will go out to it on autopilot.
To dig deeper into what mobile plans cover when it comes to international texts and roaming, the site's FAQ gathers the answers carrier by carrier, and the pricing page sets out what sending costs depending on the destination.
