Telephone Communications

How do phone call blockers work?
Answered by Science Channel
  • Science Channel

    Science Channel

  1. Phone call blockers are relatively simple devices that work on the same principle as caller ID. When we make a phone call, our phone number is transmitted along the phone line as a series of tones. Call blockers recognize any numbers you've listed as prohibited, intercept the calls before your phone rings and play a message notifying the callers that they've been blocked. Some call blockers also give you the option of requiring unknown callers to identify themselves before your phone rings.

    More answers from Science Channel »

Still Curious?
  • How do you assure uniform sound in recording a conference call?

    Answered by Science Channel

  • What happens during a typical online teleconference?

    Answered by Science Channel

  • What was the first Google phone?

    Answered by HowStuffWorks


What are you curious about?

Image Gallery