How do I block a lost SIM card?

Call your network immediately: EE on 150, Vodafone on 191, O2 on 202, or Three on 333. If calling from another phone, use the full-length numbers. They will block the SIM to prevent unauthorised use.

Will I keep my phone number if I lose my SIM?

Yes. Your phone number is linked to your account, not the physical SIM card. Once you get a replacement SIM through a SIM swap, your number will transfer to the new card.

Lost or Stolen SIM Card: What to Do

Step 1: Block Your SIM Immediately

If your SIM card has been lost or stolen, the first thing you should do is contact your network to block it. This prevents anyone from making calls, sending texts or using data on your account. The sooner you block the SIM, the less risk there is of unauthorised charges.

How to Block Your SIM by Network

Network	From Your Phone	From Another Phone
EE	Call 150	Call 07953 966 250
Vodafone	Call 191	Call 03333 040 191
O2	Call 202	Call 0344 809 0202
Three	Call 333	Call 0333 338 1001

All of these numbers are available 24/7. You will need to verify your identity, so have your account details or security password ready. If you cannot call, visit your nearest network store with photo ID.

Step 2: Report to the Police (If Stolen)

If your SIM was stolen — especially if it was inside a stolen phone — report the theft to the police. You can do this online or at your local police station. You will receive a crime reference number, which may be needed by your network or insurer.

Report online at police.uk (for non-emergency theft in England and Wales).
Call 101 for non-emergency reports.
Call 999 only if the theft is in progress or you are in danger.

Step 3: Get a Replacement SIM

Once your old SIM is blocked, you need a replacement to restore service on your number. This is done through a SIM swap. Here is what to expect:

Cost — free on all major UK networks.
Delivery — if ordered by phone or online, the new SIM typically arrives within 1–3 working days. Collecting in-store is faster.
Activation — insert the new SIM and it will activate within a few hours (up to 24 hours in some cases).
Your number — stays the same. Your phone number is tied to your account, not the physical SIM card.

Step 4: Secure Your Accounts

While your SIM is blocked and you are waiting for a replacement, take the opportunity to review your account security:

Change passwords — update passwords for email, banking and social media accounts, especially any that use SMS-based two-factor authentication.
Check for unauthorised activity — log in to your network account and review recent call and data usage for anything suspicious.
Notify your bank — if your phone was stolen and you use mobile banking, let your bank know so they can monitor for fraud.

Business Considerations

If the lost or stolen SIM belongs to a company device, additional steps are needed:

Report to your IT team or administrator — they can initiate the SIM block and arrange a replacement through your business account.
Remote wipe via MDM — if the phone is enrolled in a Mobile Device Management platform, IT can remotely wipe the device to protect company data.
eSIM advantage — if the device uses an eSIM, the profile can be deactivated remotely without needing to physically recover the device. This is one of the key security benefits of eSIM for business fleets.
Update your asset register — record the loss and the replacement SIM details in your company's device inventory.

Preventing Future Issues

Set a SIM PIN — this locks the SIM so it cannot be used in another phone without the PIN. Go to Settings > Security > SIM Lock.
Enable Find My iPhone or Find My Device (Android) so you can locate, lock or wipe your phone remotely.
Keep a record of your phone's IMEI number (dial *#06#) — your network can blocklist the handset if stolen.

Managing SIM cards across a business fleet? Connection Technologies handles provisioning, eSIM setup and SIM swaps for your entire team. Get a free quote or call 0333 015 2615.