VOICE OVER INTERNET PROTOCOL

(VOIP)

ANAND NADAR ROLL NO:26

What is VoIP ?

•Voice Over Internet Protocol is the assembling of voice into IP data. This data can then be transmitted over an IP network to an addressable ( IP address) destination

•Voice calls look like data calls •Packet switched is data that is can be routed

through different routes on a network to reach a destination

•Circuit switched is a connection where a physical path is dedicated between two end points

How does it work?

•Analog voice is received by a CODEC (coder / de-coder)

•Once sampled and matched with the codebook the voice is now presented as data

•Some codebooks are of different sizes and have a different fidelity

•These codebooks are “recommended standards” that copies voice samples into different sizes

Voice to IP Data

•Once voice is sampled and replaced by code the voice can then be formed into data and transported.

•The usual transport method uses the IP (Internet Protocol) standard.

•IP uses many layers associated with the OSI model to form, control, administer, and transport data.

•Most VoIP calls use a recommended standard that covers voice, video and data over IP networks. This standard is called H.323

•H.323 encompasses many sub-standards that control setup, signaling, transport and terminations

Voice to IP

Voice

CODEC

Compress

Create Packet

Add Headers

Network

ANALOG

DIGITAL

IP to Voice

Digital

Analog Voice

Network

Process header

Decompress

CODEC

Some of the Frequently Asked Questions

Is there a difference between making a local call and a long distance call?

Some VOIP providers offer their services for free, normally only calls to other subscribers to the service. Your VOIP provider may permit you to select an area code different from the area which you live. It also means that people who call you may incur long distance charges depending on their area code and service.

If I have VOIP service who I am?

Depending upon your service, you might be limited only to other subscribers to the service, or you may be able to call anyone who has a telephone number-including local, long distance, mobile , and international numbers. If you are calling someone who has a regular analog phone, that person does not need any special equipment to talk to you.

Some VOIP services may allow you to speak with more than one person at a time.

What are some of the advantages of VOIP?

Cost savings- The most attractive feature

of VOIP is its cost-saving potential. When we move away from pubic

switched telephone networks, long distance phone calls become inexpensive.

Instead of being processed across conventional commercial telecommunication line configurations, voice traffic travels on the Internet or over private data network lines.

Rich media service

The legacy phone system mainly provides voice and fax service even though limited video service is possible. However, the demand of users is much higher than that, as shown in today’s rich media communications through the Internet.

People check out friend’s presence, send instant messages, make voice or video calls, transfer images, and so on.

User control Interface

Most VOIP service providers provide a user control interface, typically a web GUI, to their customers so that they can change features, options, and services dynamically.

The users log in to the web GUI and change call forwarding number, speed dial, presence information, black/white list, music-on-hold option, anonymous call block, and so on.

Phone portability

The legacy phone system assigns a phone number with a dedicated line, so you generally cannot move your home phone to another place if you want to use the same number.

It is a common hassle to call the phone company and ask for a phone number update when moving to a new house.

Many businesspeople today bring their IP phones or soft phones when travelling, and use the same numbers everywhere.

Service mobility

The context of mobility here includes service mobility as well.

Whenever we change the phone, the same services could be available, such as call features, voicemail access, call logs, security features, service features, service policy and so on.

Disadvantages of VOIP

Complicated service and network architecture-

Integrated rich media services(such as voice, video, and fax)make it difficult to design the service and network architecture because many different types of devices for each service are involved, as well as different protocols and characteristics of each media.

It also causes various errors and makes it harder to troubleshoot and isolate them.

Quality of service(QoS)

Voice and video streams flow over an IP network as real-time packets, passing through multiple networks and devices(such as switches, routers, firewalls, and media gateways).

Therefore, ensuring QoS is very difficult and costs lots of time and resources to meet the users expectations.

Power outages

Legacy home phones continue to work even during a power outage because the phone line supplies 48 volts constantly.

However, VOIP phones use regular data network lines that do not provide power in most cases, which means you cannot use VOIP phones during power outages.

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