Guides

SIM, eSIM, and keeping your phone number

6 minute read · beginner

Your phone number lives with your carrier, not in your phone. That is good news when your phone dies, and a serious risk if someone convinces your carrier to move it. Both sides are worth understanding.

Physical SIM versus eSIM

A physical SIM is a card you move between phones. An eSIM is the same credential stored in the phone's hardware, installed by the carrier.

An eSIM cannot simply be popped out and moved. Transferring it means asking the carrier to reissue it, or using the transfer flow built into recent iOS and Android versions — which needs both phones working.

This matters when a phone is locked or dead: if your number is on an eSIM inside a phone you cannot use, you go through the carrier to get it back.

Getting your number onto a working phone

  1. Physical SIM: power both phones off, move the card, power on. Check that calls and texts work before doing anything else.
  2. eSIM: contact the carrier and ask them to reissue the eSIM to your new device. Have your account details and the new phone's IMEI or EID ready.
  3. Test with an actual call and an actual text. A signal bar is not proof.
  4. Only then let go of the old device.

Why your number matters more than your phone

Your number is the reset path for a great many accounts. Whoever controls it can request password resets and receive verification codes.

This is what SIM-swap fraud is: someone persuades your carrier to move your number to their SIM, then walks through your accounts. The first symptom is your own phone losing service for no reason.

If your phone suddenly loses all service and stays that way, treat it as an emergency. Contact your carrier from another line immediately.

Set a port-out PIN or transfer PIN with your carrier. It is free, it takes minutes, and it is the single most effective protection.

Never share a transfer PIN, an eSIM QR code, or a verification code. Nobody legitimate will ask for them.

Stop and get help when

  • Your line loses service unexpectedly and the carrier did not initiate it.
  • You are asked to share a transfer PIN or a QR code by anyone at all.

Official route

Your carrier's fraud team, and your bank if you believe accounts were reached through your number.

Who this is for: Account holder or authorised line manager.