Illegal scams and telemarketing calls, including recorded “robocalls”, are the #1 complaint received at the Vermont Attorney General's Consumer Assistance Program and other state and federal consumer protection agencies.  

If you are receiving these unwanted calls, there are a number of call blocking options available that you may want to consider. This is an emerging technology, and each method of call blocking has advantages and disadvantages, so be sure to review them carefully before deciding if one is right for you. 

Most device blockers currently require phone service Caller ID to be established.  In addition to the devices listed below, you may also contact your telephone provider to learn whether it will block unwanted calls, how many numbers can be blocked, and whether there is a fee for that service. Check the Customer Information Guide at the front of your phonebook for this information.


Helpful Term Definitions

  • Whitelist – A list manually programmed by the consumer for the phone to recognize and accept “safe” numbers.
  • Blacklist – Software with a preloaded list of thousands of spam numbers.
  • VoIP – Voice over Internet Protocol, such as Skype, Vonage, Magic Jack.   VoIP technology uses the internet to provide communications services rather than via the public switched telephone network.  
  • SMS – short message service or text message (i.e. text messages).
  • iOS – iPhone Operating System.

Devices for landline telephones:    

  • Digitone Call Blocker Plus: Uses black and white lisCt technology. Blocked calls are silenced. - $93.
  • CPR Call Blocker V5000 or V202:  Uses black list technology.  User can block calls as they come in and program numbers to block. - $99.
  • Landline Call Blocker: Requires user to block numbers manually by pressing a “block” button as calls come in. - $59.
  • Sentry Dual Mode Call Blocker: Callers must prove they are legitimate by listening to a recorded message and pressing “0” when prompted. The message is recorded in a British accent, which may cause some callers to think they have reached a wrong number. - $59.
  • CPR Call Blocker Protect: Uses whitelist only- so will block every call not on the list. - $50-75.
  • Telezapper TZ 900: Uses a special tone that tells predictive dialing computers that a number is disconnected. - $40.
  • T-Lock Call Blocker Version 5: Requires Caller ID to be activated. Can block incoming and outgoing phone numbers and calls without an ID. Stores the last 100 incoming and 50 outgoing calls.  - $39.
  • Pro Call Blocker Version N2: Can block entire area codes and prefixes. Blocks incoming and outgoing phone calls and calls without an ID. Stores incoming and outgoing call records. Requires password to remove blocked numbers from list. - $43.

Call-blocking apps for wireless phones:  

  • Robokiller: Winner of the Federal Trade Commission’s  2015 “Robocalls –Humanity Stikes Back” contest.   Calls are  analyzed  for audio clues that identify whether the caller is a robocall.  – Free beta format for smartphones, specifically iPhones, with an Android platform app in development.
  • Check your app store for other available technologies.

See also The Wireless Association’s web-site for information on options for limiting robocalls received by your wireless phone. 

Call-blocking services for VoIP lines (like Skype, Vonage, Magic Jack, Google Voice and similar):   

  • Nomorobo: Won the Federal Trade Commission’s 2013 "Robocall Challenge", the first public contest to develop a robocall blocker. Intercepts and compares incoming calls against black and white lists. Free for VoIP Landlines.