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8.20 PROTOCOL FOR VoIP

VoIP stands for Voice over Internet Protocol. For transferring of voice, voice over internet protocol is
used. The voice calls are first digitized, compressed and then fragmented into small packets, which
are then relayed by Internet Protocol (IP) cross network. Voice-over-IP (VoIP) implementation
enables users to carry voice traffic (For example, telephone calls and faxes) over an IP network.
So, VoIP can be achieved on any data network that uses IP, like the internet, intranets and Local
Area Networks (LAN). As the data is transmitted in the form of packets, VoIP uses packet switching
technology where each packet follows best route to reach its destination. VoIP allows both voice and
data communications to be run over a single network, which can significantly reduce infrastructure
costs.
There are 3 main causes for the evolution of the voice-over IP market:

1. Low-cost phone calls

2. Add-on services and unified messaging
3. Merging of data/voice infrastructures
Services provided by VoIP are:

Phone to phone, PC to phone, phone to PC, fax to email, email to fax, fax to fax, voice to email, IP
Phone, transparent CCS (TCCS), toll free number (1-800), class services, call centre applications,
VPN, Unified Messaging, Wireless Connectivity, IN Applications using SS7, IP PABX and soft switch
implementation.

The various protocols used for VoIP are:
1. H.323

2. Session Initiation Protocol (SIP)

CTM: VoIP is a protocol that is used for transmitting voice data and multimedia data over internet protocol.
It uses high speed broadband internet connection.

1. H.323 Protocol for VoIP

H.323 is a protocol that provides communication for multimedia services such as audio, video
and data communication over packet-based network. It specifies the standards and protocols
for all these services. As H.323 provides various communication facilities, it can be applied in a
wide variety of areas—consumer, business and entertainment applications. H.323 supports call
set-up, teardown and forwarding/transfer. A key feature of H.323 is Quality of Service (QoS). QoS
technology allows real-time prioritization and traffic management constraints to be placed on
Computer Science with Python–XII 8.42 • Audio only
“best-effort” packet delivery systems like TCP/IP over Ethernet. It can be applied in a variety of
mechanisms:

• Audio and data

• Audio and video
• Audio, video and data