A Ukrainian phone number may remain linked to bank accounts, online banking services and government platforms even after its owner moves abroad. If the number is no longer used, the mobile operator may eventually reassign it to another subscriber, potentially putting personal data and funds at risk.

According to the Ministry of Economy, Environment and Agriculture of Ukraine, more than 5.7 million refugees from Ukraine were recorded in 2026, with the largest numbers residing in Germany, Poland and the Czech Republic.

People may go for extended periods without using their Ukrainian mobile phone numbers. However, if the account balance is not topped up at all, the operator may eventually deactivate the number and make it available for reassignment to a new subscriber.

Criminals deliberately acquire numbers that have become available for reassignment and check whether they are linked to the previous owners’ accounts and online banking services. In this way, criminals may gain access to other people’s accounts, including the online banking accounts of former number holders.

To reduce these risks, Ukrainians living abroad should take steps in advance to protect their mobile phone numbers:

1. Keep your Ukrainian SIM card secure and do not lose control of your number. Check with your mobile operator to find out the requirements for keeping your number active and how often you need to take action to maintain it.
2. Protect your number against unauthorised SIM replacement. Ask your operator whether you can register the SIM card in your name using your identification documents, restrict remote SIM replacement or introduce additional identity verification measures. Available options depend on the operator and its procedures. Use only official applications and customer support channels.
3. Secure your mobile operator account. Set a strong, unique password and enable two-factor authentication, if available. Never share SMS verification codes with third parties, even if the person contacting you claims to represent your mobile operator, bank or customer support service.
4. Check which services are linked to your phone number. Pay particular attention to bank accounts, email accounts, social media profiles and government services. Where possible, enable additional security measures for important accounts that do not rely solely on SMS verification.
5. Consider using a separate phone number for financial transactions. Avoid publishing this number in advertisements, public profiles or on third-party websites unless necessary. The fewer people and services that know the number used for financial transactions, the fewer opportunities criminals have to gain access to your accounts and drain your funds.

If your Ukrainian SIM card suddenly stops working for no apparent reason, do not ignore it. Contact your mobile operator through an official channel and check whether any actions have been taken in relation to your number. If you suspect that your number has been hijacked, notify your bank as soon as possible and check the security of all linked accounts.

We emphasise: never share verification codes, passwords or login credentials for personal accounts with anyone.

If you no longer intend to use your Ukrainian phone number, first unlink it from important services and only then give it up.

For more digital security advice, visit the Cyber Brama platform.