Provide them with your IMEI number and account details. Most carriers will provide the unlock instructions or remotely authorize the device if the eligibility requirements (such as completing a contract) are met.
: Ensure your modem is eligible for unlocking. Most carriers have policies that allow unlocking after a certain period, usually after the contract has ended or after a specific period of time has passed. unlock modem zte m26z1z
Alternative: Use AT command (advanced)