What is the exact message you're getting?
If you're getting "SIM network PIN blocked. Enter SIM network PUK." on a Samsung phone then you can call Samsung at 1-800-726-7864 and they will give you a code to unlock it. They'll want the IMEI of the phone in question.
If any of "SIM network unlock PIN", "SIM ME lock code NP", "SIM not Supported", "SIM locked", "Network Unlock Code", "SIM PUK code", "Network Control Key", "Master Unlock Code", "Network PIN" means that the phone is locked to a previous provider. You'll need to contact them to unlock the phone.
If any of "PIN unlock key (PUK)", "Enter PUK Your SIM cannot be accessed", "Locked SIM" then that can be helped by contacting support https://productioncommunity.publicmobile.ca/t5/notes/composepage/note-to-user-id/22437
