• Question: why is it possible to call person in far place

    Asked by bank22dee on 16 Jul 2025.
    • Photo: Justa Mwangi

      Justa Mwangi answered on 16 Jul 2025:


      The ability to instantly connect with someone across vast distances, whether in another state or across the globe, is made possible by a sophisticated network of technologies that transmit your voice as electrical signals.

      Here’s how it works:

      Voice to Electrical Signals: When you speak into a phone, a microphone converts the sound waves from your voice into electrical signals.
      Transmission via Cables or Radio Waves: These electrical signals then travel through a network of infrastructure, which can include:
      Copper Wires: The traditional landline system uses twisted pairs of copper wires to transmit electrical signals over short distances to a local switching office.
      Fiber Optic Cables: For longer distances, especially across continents and under oceans, fiber optic cables are the primary medium. These cables transmit your digitized voice (along with thousands of other conversations) as light pulses, offering significantly higher bandwidth and speed than copper wires.
      Cell Towers and Radio Waves: For mobile phones, your voice is converted to electrical signals, then transmitted as radio waves to a nearby cell tower. The cell towers relay these radio waves to the cellular network, which in turn routes the call.
      Satellites: In some cases, particularly in remote areas or for international calls, signals may be relayed via satellites. Satellites in orbit receive signals from ground stations, amplify them, and retransmit them to other ground stations, bridging the communication gap over large geographical areas.
      Switching Centers and Routing: As your call travels through this network, it passes through various switching centers and routers. These computerized systems analyze the phone number dialed and direct the call to the appropriate destination by connecting to different local and long-distance carriers.
      Digitization and Multiplexing: To efficiently transmit multiple calls simultaneously over the same lines, particularly over long distances, your voice is digitized (converted into a stream of data) and combined with other calls. This process, known as multiplexing, allows for a tremendous increase in the capacity of the network.
      Electrical Signals to Voice: At the receiving end, the electrical signals, whether transmitted by wires or radio waves, are converted back into sound waves by the receiver’s phone speaker, allowing them to hear your voice.

      In essence, a complex interplay of physical infrastructure (wires, cables, cell towers), specialized equipment (switches, transponders), and sophisticated algorithms for data processing and routing work together to create the seamless experience of making a long-distance call.

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