VoIP Voice Transport Layer Protocol

VoIP calls cross the Internet over the user datagram protocol.

The dominant protocol suite for networks is transmission control protocol/Internet protocol (TCP/IP). This dominance extends to the Internet, where a component, the Internet protocol, is responsible for standardizing all addresses. Within the suite, there is one protocol which is especially favored for use with voice over Internet protocol (VoIP) applications.

Features

Networking protocols are grouped by function and represented as layers in a stack. Each layer has responsibility for a particular task in transferring data. The transport layer is responsible for establishing connections, packetizing data and ensuring data integrity. There are two main transport layer protocols: TCP and user datagram protocol (UDP). Of these, UDP is preferred for VoIP traffic.

Function

The UDP is lightweight. TCP offers many services integrated into the VoIP application. TCP establishes a connection, but VoIP uses the session initiation protocol (SIP) for that. TCP also checks the sequence of arriving packets and notifies for missing packets, buffering arriving data until the correct order of packets has been assembled. This slows down VoIP packages.

Purpose

UDP was not popular until multimedia applications came along. Since then, UDP is part of the cutting edge of networking technology. It is the preferred transport layer protocol for VoIP and video-streaming applications.

References

• Internet Engineering Task Force: Request for Comments 768