Blog

  • VoIP: Advanced Circuit Switching and Packet Switching

    by Matt Peterson on Monday, August 27th, 2012.

    Voice over Internet Protocol (VoIP) relies on advanced circuit switching to operate effectively. Traditional telephone systems are driven by circuit switching, a reliable but somewhat inefficient method.

    Circuit switching is the result of two parties making a telephone connection, which is maintained the entire duration of the phone call. When two points are connected, this is known as a circuit.

    A traditional telephone service works in the following manner:

    1. A caller picks up the receiver and listens to confirm a dial tone. This indicates that there is a connection to the local telephone carrier.
    2. The caller dials a party’s number.
    3. The call is routed through a switch at the local telephone carrier.
    4. A direct connection is made between the caller and the caller’s receiver, which uses several interconnected switches in the process.
    5. The receiver at the other end rings and the phone is answered.
    6. When the phone is answered, this opens a connection, thus forming a circuit.
    7. Once the parties speak and conclude the conversation, the receiver is hung up.
    8. When both parties hang up, the connection closes the circuit. Long ago, copper wiring stretched from city to city. The reason long-distance telephone calls were so expensive is that telephone companies charged for “ownership” of those lines during telephone calls.

    With modern, advanced technology, traditional telephone systems now cost significantly less and are much more efficient than their predecessors. Today, telephone companies digitize voices into a single fiber optic cable. These are then transmitted at a fixed rate of approximately 64 kilobits per second (Kbps). Because this is the rate in each direction, the total transmission rate is 128 Kbps.

    A packet-switched telephone network is the only alternative to traditional circuit switching. This enables packets of information to only be heard when bytes are created. Essentially, dead space or silent filler requires a small amount of space. Instead, packet switching sends data when it detects noisy bytes.

    Data networks do not utilize circuit switching. Contrary to popular belief, Internet connections do not maintain a constant connection to web pages. Instead, the networks simply retrieve and send data as necessary, or when it requires an update. Instead of data packets being transmitted over the line, they are transmitted via packet switching.

    Packet switching is extremely effective for VoIP businesses, sending data in small packets to network devices. When the receiving computer receives these small packets of information, it reassembles them into one massive file. This highly efficient VoIP hosted method helps decongest network lines, and allows business phone systems to remain free on each end.