VoIP(Voice over Internet Protocol)
VoIP (Voice over Internet Protocol), differently voice communication is done through PSTN (Public Switched Telephone Network), make voice communication possible through Internet network. VoIP uses Packet-based network instead of PSTN, so there is no telephone bill and VoIP is inexpensive. Not only audio data but also video data can be transmitted, because VoIP uses H.323 Protocol of ITU-T standard.
Communication Types

  • PC to PC
    Method using protocol such as H.323 after compressing by speaker and microphone(G.723, G.729 CODEC)

  • PC to Phone
    Same method with PC to PC in one side, but the other is regular telephone.

  • Phone to Phone
    Both sides are using regular phone. Instead of PSTN, long distance call can be possible through Internet Phone Gateway which the service provider offers.

  • Fusion Board
    Controlling Inbound or Outbound Call
    Transferring Analog Voice Data to Digital Voice Data

  • H.323 Protocol
    H.323 is ITU's standard protocol to provide communication between two networks in real time,
    and is mostly standard protocol in the Internet phone field.

  • System Diagram

    User Application
    AV Control & management DATA
    Audio Video RTCP RAS GK Signaling H.255.0 Call Signaling H.245 T.12X Data Protocols
    RTP
    UDP TCP
    IP

  • G.723.1 Vocoder
    PCM voice data of regular phone line is not proper for communication through Internet because it has the bandwidth of 64kbps. Different types of development to accept more lines in small bandwidth has manifested. One of them is G.723.1 and can compress 64Kbps voice data to 6.4Kbps.
Application Field
  • Intranet: Connection to the company branch
  • PSTN Service: more than 100 users
  • Consulting Service
  • Customer Service
  • Video Phone
  • Internet Call Center
  • UMS over the Internet
  • Web-based Call Management
  • Web-enabled IVR
  • FoIP : Fax over Internet Protocol