Getting spam calls from a particular area code or number range can be bothersome. Fortunately, with the Robokiller app on your Android device, you can easily block them! Here’s how to do it:

1. Open the Robokiller app and tap Settings.
2. Choose Blocked and allow list, then select Blocked List.
3. Tap + in the bottom right-hand corner, then A number to add an area code or number range.
4. Enter the area code or number range and select Block to add the number to your blocked list. Optionally, you can add a label for quick identification. 

After setting this up, any incoming calls from the area code or number range you added will be blocked. Rest assured, calls from numbers saved in your contacts will always come through, as Robokiller ensures your important calls aren't missed.