Phone number recycling: why codes reach strangers
Numbers are reassigned. What the rules say, how services react, and what it means for a temporary number.
What do the rules say?
US federal rules set an "aging" period: "Numbers previously assigned to residential customers may be aged for no less than 45 days and no more than 90 days." Business numbers may be aged up to 365 days. The FCC also runs a Reassigned Numbers Database that callers can use "to determine whether a telephone number may have been reassigned".
How do services plan for it?
| Service | What it says |
|---|---|
| Apple | "After 30 days, another user might be able to associate that phone number with a different Apple Account." |
| Expects carriers to recycle numbers; account data tied to a number can be removed when a new owner activates it after 45 days | |
| OpenAI | Removes the phone number 30 days after a ChatGPT account is deleted |
| Telegram | "Make sure you have access to your connected phone number — otherwise you risk losing access to your account." |
Checked 2026-10-18.
Security guidance goes the same way: NIST classes phone-based verification as "restricted" and tells verifiers to weigh "SIM change, number porting" and similar signals.
What does this mean for a temporary number?
A single-use number is for one code from one service. It is not kept for you afterwards, so do not use it for an account you need to recover later. Use it to receive one code, then add a passkey, an authenticator app or an email you control as the account's recovery method.
For accounts you log into again and again, a rental keeps the same US number for 7 or 30 days.
Keep a US number for 30 days
One service or any service.
Frequently asked questions
Can I use the same number again later?
A single-use number is for one code from one service. It is not kept for you afterwards, so do not use it for an account you need to recover later. For a number you keep for days or weeks, see the US rentals.
Can someone receive my codes after I use a number?
Yes, once the number is reassigned. That is why you should never leave a temporary number as the recovery phone of an account.
Sources
- 47 CFR 52.15: number aging (checked 2026-10-18)
- FCC: Reassigned Numbers Database (checked 2026-10-18)
- Apple Support: change your Apple Account phone number (checked 2026-10-18)
- WhatsApp Help Center: recycled numbers (checked 2026-10-18)
- OpenAI Help: phone verification (checked 2026-10-18)
- NIST SP 800-63B rev. 4 (checked 2026-10-18)