Call blocking

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Call blocking, also known as call block, call screening, or call rejection, allows a telephone subscriber to block incoming calls from specific telephone numbers. This feature may require an additional payment to the subscriber's telephone company or a third-party.

Call blocking is desired by individuals who wish to block unwanted phone calls. These generally include types of unsolicited calls from telemarketers and robocalls.


Unwanted calls to landlines may be blocked through a number of methods. Some landline phones have built-in call blocking facilities. External call blockers are sold as telephone accessories which plug into existing phones.

Call blockers and related services recently received attention in 2016 from publications including Which? and Consumer Reports in the United Kingdom and United States respectively.[1] [2] Such devices and services enable the user to block a call as it is in progress or alternatively block the number after the call is made. These devices rely on caller ID information and thus a phone operator requires a caller ID service active on the line for blocking to function.

Landline call blocker in use

It may also be possible to use computer software, in conjunction with the caller ID information from the phone company and a caller ID enabled phone modem to block an incoming call.

Treatment of blocked calls may include:

  • Sending caller to voicemail
  • Sending caller to busy signal
  • Sending caller to "Number No Longer in Service"
  • Sending caller to "Keep Ringing"

Cell phone[edit]

There are a multitude of third-party call blocking applications available for smart phones while some manufacturers provide built-in call blocking functions as standard.[3]

See also[edit]


  1. ^ Leedham, Robert. "Call blocking devices – everything you need to know". Which?. Retrieved 13 January 2016. 
  2. ^ "Rage against robocalls". Consumer Reports. Retrieved 13 January 2016. 
  3. ^ "How to block phone calls on your Android phone". Digital Trends. Retrieved 13 January 2016.