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Phones & Tablets

How do I request a SIM swap if I cannot remember the old phone number?

Reviewed by John Porter, Editor ·

Answer

Carriers usually identify the line with the account holder’s name, PIN/passcode, billing details, or IMEI/SIM details—not only the phone number. Recover the number from old bills, emails, the previous phone’s About/SIM status screens, or the carrier account, then complete the SIM change only through the carrier’s official app, store, or verified support.

Before you start: stop right away if…

  • Never share carrier account PINs, passwords, or one-time codes with unexpected callers—SIM-swap scams are common.
  • Activating a new SIM typically disconnects the old SIM right away.

Follow these steps

  1. Search old records for the number

    Check carrier emails, PDF bills, payment receipts, and contacts backups for a 10-digit mobile number on that account. Also check any old phone under Settings > About phone / Status / SIM status for the number if it is still shown.

    You should see: You recover the phone number or enough account identifiers to continue.

  2. Sign in to the official carrier account

    Open the carrier’s official website or app and sign in. Look under Lines, Devices, or Account for the mobile number, IMEI, and SIM details.

    You should see: The line details appear without needing the number from memory.

  3. Start the SIM or eSIM change officially

    In the carrier app or at an official store, choose transfer/activate SIM or eSIM for that line. Complete identity checks the carrier presents. Insert the new SIM or follow eSIM install prompts only from the carrier.

    You should see: The new SIM or eSIM activates and shows service bars.

  4. Confirm calls and texts on the new SIM

    Place a test call and send a test text. Update important accounts that used SMS verification once the new SIM is working.

    You should see: Voice and SMS work on the new SIM, and the old SIM no longer carries the line.

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Extra tips

What to look for: Old invoices showing the mobile number; carrier account profile; About phone / SIM status on an old device; account PIN or last-four of payment method the carrier asks for

Before you change anything: Gather photo ID and account proof the carrier normally asks for. Use only the official carrier app, website, or store—not a random text link. Do not share account PINs or one-time codes with unexpected callers. Know that a SIM swap moves service away from the old SIM immediately.

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