VoIP Voice Over Internet Protocol

VoIP Voice Over Internet Protocol



VoIP Architecture
VoIP Gateway
Signalling Protocols
VoIP Terminals
Advantages and Disadvantages

PSTN Public Switched Telephone Network

  • It is known as landline telephone system.
  • It was designed for purely analog voice communication by using wire network. It meant higher cost for long distance.
  • Number of switches are involved to establish a connection.
  • PSTN uses circuit switching. Dedicated path.

VoIP Voice Over IP

  • Voice over Internet Protocol (VoIP) is a technology that allows users to make phone calls using internet.
  • It is also known as IP telephony, Internet telephony or internet calling.
  • The voice (and data) messages are split into packets by using digital signal processors (DSPs).
  • VoIP uses packet switching. No dedicated path.
  • Its is very cheap or Free. It uses the existing infrastructure of internet.

VoIP Gateway

  • A VoIP gateway (or PSTN Gateway) is a device which converts telephony traffic into IP for transmission over a data network.
  • Perform DSP.
  • Call Control.
  • Bandwidth Management.


  • Data Compression.
  • Data Encoding.

Codec are  of different types for data, voice, and Video. The quality and efficiency of the compression software has a big impact on the voice quality of VoIP traffic. There are good compression technologies and there are less good ones. Each compression technology is designed for a specific use under specific circumstances.

Signalling Protocols

The signaling protocols govern the set-up and to many other related call management functions.


It is ITU-T standard protocol.It is actually a set of protocols .H.323 was designed for multimedia communication services such as real-time audio,video, and data communications over Ip Network.

SIP (Session Initiation Protocol).

It is IETF standard protocol and younger than H.323,it is lighter (requires less bandwidth). It is text-based. It is specially design for VoIP services.

SCCP (Skinny Client Control Protocol).

This is a proprietary CISCO signaling protocol used by CISCO products.

Share This Post

Post Comment