Skype work technically:

• Voice-over-internet-protocol (VoIP) is Skype's primary technology. Your call will be carried through an Internet connection rather than a phone line with this method. Unlike a phone service, the Internet does not charge more to send data around the world than it does to send it to your neighbor's house.
• This means that Skype can charge far less for long-distance and international calls than phone providers while still making a profit. VOIP merely transforms your voice (and, in video calls, your image) into computer data. It lowers the audio quality in order to decrease data usage.
• Skype programmes are available for a variety of smartphone platforms, allowing you to make and receive Skype calls directly from your phone. This may be perplexing because you aren't exactly making a phone call in the traditional sense: Instead, you use an Internet service and your phone handset as a speaker and microphone.

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