I agree with @KMG, if you're getting that message, your phone might be locked to your old carrier. You should request for an unlock code from your old carrier to have your phone unlocked, prior to being able to use Public Mobile 🙂
If you insert the SIM card and receive a network lock message, that probably means that your phone is locked and needs to be unlocked before it can be used with Public Mobile.
* I am happy to help, but I am not a Customer Support Agent please do not include any personal info in a message to me. Click HERE to create a trouble ticket through SIMon the Chatbot *
