Check whether the phone accepts SIM cards from different carriers
Insert a SIM card from another carrier and see if it connects to the network
Look in the phone’s settings for carrier lock or network lock status
Contact the original carrier and ask if the device is unlocked
Use the phone’s IMEI number to check unlock status with the carrier or manufacturer
Try making a call, sending a text, or using mobile data with a different carrier SIM
If the phone works with multiple carriers, it is likely unlocked
If the phone shows a SIM not supported or network locked message, it is likely locked