Kurt "Cyberguy" Knutsson outlines the simple steps to block unknown calls on your Android and iPhone so you can avoid those spam calls.

How to block No Caller ID calls on your Android Phone For those wishing to block incoming calls that present as ‘ No Caller ID ‘ or ‘ Withheld Number ‘ on your Android device, the ...

How to block your phone number for every call If you don't want anyone to see your phone number when making calls, you can follow these directions. Step 1: On your Android phone, select the Phone app.

If you’ve got an Android phone, the simplest way to block a number is straight from the Phone or Messages app. Tap the number, select “Block,” and that’s it. For more control, go to: ...

Android now lets you block entire number ranges to combat spam and telemarketing calls.