In addition to registering your phone numbers on DoNotCall.gov (this will stop legitimate telemarketers), you can now (as of last week we believe) take action to block a specific set of numbers from reaching your Time Warner digital phone.
Simply browse on over to My Services on the Time Warner cable website, and register to create an account if you haven't already. Then, log in and click on "My Home Phone." From there, you'll see a "VoiceZone" section. Click on the "Go to VoiceZone" button, and then browse down the list and select "Selective Call Blocking."
On this screen, you'll be able to enter up to 30 numbers that will not be able to reach you. Their calls will not appear on Caller ID, go to voicemail, or get forwarded. They will simply hear a pre-recorded message that says "The called party is not accepting calls from this phone number."
Once you're done adding phone numbers you'd like to block, hit the "add changes to save queue" button. Finally, in the right-hand column of the screen, you'll see a list of changes waiting to be saved. Click on the "Save" button to confirm the changes.
If you ever want to remove a number from the blocked list, browse back to "selective call blocking" and select the "remove" button next to the phone number you wish to remove. You'll need to re-save your changes.