One of the most common reasons for a non-working SIM is due to your mobile device being locked to an operator back home. We recommend first testing the SIM card in another phone or device, to ensure that it works in an unlocked phone.
If you're still having trouble, we recommend contacting the local operator for your SIM card. We always include the operator's contact details in your instructions letter, and they should be able to assist you.
If not, contact us, we will do our best to fix it. Our Support team is available, so mail, chat with us or call us. If we still can’t get things working for you, you can send the SIM back to us, and we’ll test it. If the SIM is deemed defective, we’ll refund you. Just make sure you contact us to let us know.