VoIP stands for Voice over Internet Protocol, is a protocol designed for transferring audio (voice) over the Internet. This protocol can be referred by different terms like IP telephony, Internet telephony, broadband telephony etc., this protocol helps in routing or directing the voice conversations in any IP based networks.
VoIP protocol helps to maximize the use of under utilized cable line that can transfer large amount of data. VoIP protocol is used to make voice conversation between two IP based systems, or between PSTN and VoIP system.
VoIP allows users anywhere in the world to make and receive phone calls from other voIP system:
1. Instant Messenger based VoIP services can travel anywhere in the world and make and receive phone calls.
2. Specialized mobile VoIP services enable users to talk over IP (Internet Protocol) and use VoIP based instant messaging services from their mobile phones.
3. VoIP phones can integrate with other services available over the Internet, including video conversation, message or data file exchange in parallel with the conversation, audio conferencing, managing address books and passing information.
Need for voIP:
The IP based networks used UDP to transfer voice in the internet. But UDP does not ensure that data packets are delivered in sequential order, or provide Quality of Service (QoS ) guarantees ( due to packet loss and no acknowledgement) , VoIP implementations face problems dealing with latency and jitter . When the round trip time for a system in network is high, jitter occurs so in order to overcome this VoIP provides jitter buffer.
VoIP enables to overcome following difficulties that occur in IP based network. The challenges are:
1. Delay/Network Latency
2. Packet loss
3. Jitter
VoIP rectifies this by following technique:
1. Fixed delays cannot be controlled but some delays can be minimized by marking voice packets as being delay-sensitive.
2. The principal cause of packet loss is congestion; Carrier VoIP networks avoid congestion by means of traffic engineering.
3. Variation in delay is called jitter. The effects of jitter can be mitigated by storing voice packets in a buffer (called a play-out buffer) upon arrival, before playing them out.
For more information on VOIP read What is VOIP
