For iPhone

Method 1: Using Settings

1. Open the Settings app.
2. Go to General > About.
3. Scroll down to the Carrier Locksection.
   • If it says "No SIM restrictions," your iPhone is unlocked.
   • If it says something like "SIM Locked" or lists a carrier, your iPhone is locked.

Method 2: Testing with a Different SIM Card

1. Insert a SIM card from a different carrier.
2. Restart the phone.
3. Check if the phone connects to the network.
   • If it doesn’t and displays a message like "SIM not supported", the iPhone is locked.

For Android

Method 1: Using Network Settings

1. Go to Settings.
2. Navigate to Connections or Network & Internet (this may vary by device).
3. Check for options like Mobile Networks or Carrier Settings.
   • If you see an option to choose a network manually and it works with other carriers, your device might be unlocked.

Method 2: Testing with a Different SIM Card

1. Power off your phone.
2. Insert a SIM card from a different carrier.
3. Restart the device.
   • If the phone connects to the network, it’s unlocked.
   • If it shows messages like "SIM not supported" or "Network locked," the phone is locked.

Method 3: Dialing a Code

1. Open the phone app and dial *#7465625# or *#*#7378423#*#*.
   • Some devices (e.g., Samsung) may display the SIM lock status with this code.