Basics Voip

Voice Over Internet Protocol

By Sanjeet Singh

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Voice Over Internet Protocol 1. Introduction 2. Need of VoIP 3. Functionality 4. Want of it. 5. How It Works? 6. VoIP Protocols 7. Security 8. VoIP in INDIA 9. Conclusions

1. Introduction • Very simply, VoIP, or Voice over Internet Protocol, is the technology that allows us to have phone service over the Internet. • VoIP may be a new term for you, but the technology isn’t new. • The telephone companies, who use what is referred to as the public switched telephone network (PSTN), have been employing VoIP technology for years.

2. Need of VoIP • The most obvious answer is to save money. • VoIP acts as a bridge between your Internet connection and the PSTN. • Allowing you to have phone service without requiring an account with the phone company. • That, coupled with VoIP’s unique pricing model, means that users can often cut their long-distance calling expenses dramatically.

3. Functionality • Ability to transmit more than one telephone call down the same broadband-connected telephone line. • Many VoIP packages include PSTN features. • VoIP is location independent. • VoIP phones can integrate with other services available over the Internet.

4. Why we want it? • The most obvious answer is to save money. • VoIP acts as a bridge between your Internet connection and the PSTN. • Allowing you to have phone service without requiring an account with the phone company. • That, coupled with VoIP’s unique pricing model, means that users can often cut their long-distance calling expenses dramatically.

5. Working • VoIP works by taking analog signals and converting them to digital data that can be sent over a network—the Internet in most cases, also any private network. • It requires that you have a broadband network connection, the necessary items to create that broadband connection— • a broadband modem, your computer, a router, etc.—and a device to convert the data.

6. Protocols used in VoIP

• • • •

Session Initiation Protocol (SIP) Megaco(H.248) Skinny Client Control Protocol MIME

SIP – SIP is an application-layer control (signalling) protocol for creating, modifying and terminating sessions with one or more participants. – Sessions include Internet Multimedia, conferences, Internet Telephone calls and Multimedia distribution. – Provides toolkit (methods, headers) from which features can be assembled

SIP contd….

• Message Waiting Indication about to be published • Call transfer, history information (for call diversion), presence, instant messaging under study.

Megaco Media Gateway Control Protocol • This protocol creates a general framework suitable for gateways, multipoint control units and interactive voice response units (IVRs).

Skinny Client Control protocol

The skinny client (i.e. an Ethernet Phone) uses TCP/IP to transmit and receive calls and RTP/UDP/IP to/from a Skinny Client or H.323 terminal for audio. Skinny messages are carried above TCP and use port 2000.

MIME This set of standards, collectively called the Multipurpose Internet Mail Extensions, or MIME, redefine the format of messages to allow for textual message bodies in character sets other than US-ASCII, an extensible set of different formats for non-textual message bodies, multi-part message bodies, and textual header information in character sets other than US-ASCII.

Skype

Skype is a software program created by the entrepreneurs Niklas Zennström and Janus Friis. Skype allows users to make telephone calls from their computer to other Skype users free of charge, or to Landlines and cell phones for a fee

7.VoIP Security VoIP, because it uses the Internet as its conduit, is subject to the same sorts of attacks as any other Internet traffic.  Your VoIP network can suffer from viruses, Trojans, denial-of-service attacks and other sorts of dangers such as a SYN flood or Ping of Death. It's also possible for an attacker with publicly available hacking tools to intercept VoIP packets and eavesdrop on your conversations.

8.VoIP in INDIA

In India, it is legal to use VoIP, but it is illegal to have VoIP gateways inside India. This effectively means that people who have PCs can use them to make a VoIP call to any number, but if the remote side is a normal phone, the gateway that converts the VoIP call to a POTS call should not be inside India.

Major VoIP Providers in India – Sify, Tata Indicom, MTNL&VSNL.

9.Conclusions – Evolution of the voice network is important to many enterprises – Traditional and IP networks will continue to coexist in the enterprise – Exploitation of new services and applications in IP network – But needs to be complemented by extending existing services to IP and mixed environments