Block Unwanted Calls

If your Direct Line number is getting spam calls more often then you can block particular numbers in the Blacklist to stop receiving calls from those numbers
Block a particular number:

1. Settings – Blacklist
2. Enter the number in the box
3. Choose Block

Anonymous Calls: Anonymous calls are blocked by default. Otherwise, click the Unblock icon beside the Status.
Import from Recent Calls: 

1. Click Import from the recent calls
2. Select the numbers you wish to Block
3. Choose Import