Introduction The term VoIP involves the migration of Voice over Internet Protocol (IP) TCP / IP protocol suite. Using VoIP technology we can make regular phone either from a computer or a computer or mobile phone using the public switched telephone network two (PSTN) and Internet (which is a packet switched network). You need an internet connection for VoIP. Real change all this technology, because it allows people to receive a call from a mobile Internet connection wherever it was, just the same way you can receive your email anywhere that you can connect to the network.
VoIP technology includes a variety of technologies, including voice-over-IP (VoIP) and fax-over-IP service, which is two more than you make the Internet and private IP-based networks. VoIP is part of the sound package, which includes voice-over-asynchronous transmission-mode (ATM) and frame-relay network, which travel faster than IP but is less common. VoIP connects PCs throughout the novel, web-based phone, and the phone is connected via the public telephone lines for rural voice gateway. Because the information that moves in Discrete package, so it does not need to rely on circuit switched continue to be available.
Using VoIP can enhance traditional PBX services combining voice and data on one network. End user device (also called a client device) is usually referred to as VoIP phones that are used in VoIP. VoIPphone development will require the development of a system that combines digital signal processing chip (DSP) performance, micro-ruler (MCU) functions, analog interfaces, mobile user interface and associated glue logic.
Uses of VoIP The VoIP service is used in business and service network for various reasons. Many of these can be included in the following.
Ø Better use and Bandwidth:
§ Using compression
§ use the period of silence during the negotiation
§ Participation of equipment for voice and data traffic (integrated manufacturing)
Ø Introduction of new services:
§ Conferences, distance learning, etc.
Working of VoIP Basic steps involved in originating a VoIP call to conversion of analog voice signals into digital format and compression / translation of the signal into Internet Protocol (IP) packets for transmission over the Internet, the process and then leave the recipient - a digital switching telephone analog format so that normal . VoIP started back as an incoming call through the broadband: Coaxial cable, DSL ( Digital Subscriber Line), wireless or even satellite. The call is routed to the VoIP Company, where a computer converts the sound into data packets - similar to the packets used to transfer internet data such as email. Sending data by packets is far more efficient as it enables the same line to handle more information simultaneously. These data packets are sent through any of the Internet s multiple networks to a recipient of the call. The caller can receive the call via a wireless provider, a broadband provider, or a local phone carrier. In order to understand VoIP it is essential to have a complete understanding of what the difference between circuit switching and packet switching. A normal telephone uses circuit switching for phone calls, which involves routing of your call through the switch at your local carrier to the person you is calling. The connection of two points in both directions is known as circuit. Packet switching on the other hand is more efficient in transmitting data since small amount of data, which is called a packet, is sent from one system to another. In a VoIP system, once the called party answers, voice must be transmitted by converting the voice into digitized form, then segmenting the voice signal into a stream of packets. The first step in this process is converting analog voice signals to digital, using an analog-digital converter. Since digitized voice requires a large number of bits, a compression algorithm can be used to reduce the volume of data to be transmitted. Next, voice samples are inserted into data packets to be carried on the Internet. The protocol for the voice packets is typically the Real-time Transport Protocol (RTP). RTP packets have special header fields that hold data needed to correctly re-assemble the packets into a voice signal on the other end. However, voice packets will be carried as payload by UDP (User datagram protocol) protocols that are also used for ordinary data transmission.
ADVANTAGES Here are some of the benefits of VoIP:
ü VoIP is cost - using VoIP products and long distance telephone calls and international calls can be made in local phone rates. Only the caller is connected to the Internet (for the price of local phone internet provider) and using the right program, calling other similar computers running VoIP applications, or even another phone anywhere in the world. (Major PC-2-Phone VoIP Gateway conversations need to be present in rural areas).
The number of growing operator worldwide communication using VoIP as a means of modern communication for long distance calls using a full-Phone-2 Phone conversation, which was published in IP networks. (Fully transparent to the caller) Using voice networks for IP transport allows for a lot of phone calls made at the same time, thus reducing operator costs. In addition, companies can use their Intranet as a business in their mobile networks (iPBX). This makes it possible to reduce maintenance costs, and affordable communications area of the branches of the organization.
ü Convergence - By using VoIP, a company can overcome two broad data management and telecommunications, all on one platform and supported by one vendor. This allows companies to use one system for all their needs and prevent the communication overhead caused when dealing with several software packages and platforms.
ü Maintenance (upgrades to existing services or introduce new services) can be done easily, because many applications are right in accordance with the program that does not require replacement of equipment and configuration.
ü Net Smart - Be based on software, products and VoIP services allow intelligent solutions. Successful management of the power level of PSTN equipment requires significant changes in many VoIP solutions can be easily managed with mouse clicks. An example of call routing may be used in ways that have been established: the schedule is set, and all telephone calls are diverted various areas (eg Home, Mobile, Business, and Voicemail) on schedule. Major strengths in VoIP networks is trivial (software solutions), so far as the PSTN function requires much effort.
ü New age Multimedia - Because we treat voice as data and the fact that we can use the service and voice telephony services from our PC, we can use as a voice of our prayer requests from other computers. That way we can use materials the same and browse the internet, talking on the phone and the other working visit at one time and there is no change between devices. This idea is also part of the benefits of convergence brought here in this section.
ü The evolution of communication better service - For all the above, the transformation toward VoIP is the best communications services. We can combine streaming video with sound for a conference call, which allows the best multimedia applications using all types of networks and services provide customers with better communication (as a smart net) for secure communications package that will be customized and configured to supply the needs of each customer.
Main Issues of VoIP For VoIP to become popular, some important issues that need to be resolved. Some of these issues comes from the fact that IP is designed for transporting data while some issues arise because the vendor is not in accordance with the standards [3].
Important issues are discussed below.
Interoperability In general networks, products from various retailers need to work for all people if Voice over IP is common among users. Achieving interoperability, standards and yamewapotea is that the general standard for VoIP is H.323 standard.
Security This problem exists because the Internet, anyone can capture packets for others. Using encryption and tunneling to provide security. Tunneling protocol commonly used layer 2 Tunneling protocol and procedures commonly used encryption Secure Socket Layer (SSL).
Integration with Public switched Telephone Network (PSTN) When Internet telephony was introduced, will need to work in collaboration with the PSTN for many years. We need to PSTN and IP telephony networks appear as a network for users of this service.
Scalability If researchers are working to provide high quality IP phone as usual but at a very low cost, so there is great potential for high growth in VoIP systems. VoIP systems require flexible enough to grow the market and let users mix of private and public.
VoIP technology can produce cost savings for all companies and consumers. Was more effective than regular old telephone service (POTS) is a large and ready for growth through. Before that growth can occur, however, has DESIGNERS issues mentioned above.
Although the issues described above, provide sound quality is better for customers is another challenge. Introduction to VoIP number of potential interference that can affect sound quality disadvantages, such as the use of lossy nature-bit-rate codecs's, the effect of tandem encoding / transcoding, longer delays, and packet loss. Many of these disorders is not well today or in the cycle a bit switched networks. Thus, new strategies for providing and maintaining the sound quality required for VoIP networks. The damage that the voice call experience can be classified as either architecture or load dependent.
Codec IP architecture components with their phone and setting configuration parameters as well as fixed components such as delayed processing delays at each network element along the road and end-to-end propagation delay. This architecture defines the components bound in the best sound quality that can be found in a given network. If bound over is not acceptable, then the material and configuration changes will be needed. In general, if the design satisfactory, then the packet delay and loss characteristics sufficient to ensure good voice quality.
Load dependent damage including packet loss, delay lines, and Matter. As the load increases, these parameters started to deteriorate and destroy the sound quality. The sound quality user experiences depends on the character of the entire end-to-end connections. This relationship can cross multiple domains and networks put all the control and management techniques. Damage in the opposite relationship is cumulative, there is the possibility that each domain networks declared sound quality received on end to end does not have a relationship.
Network services, offering end applications can be measured quantitatively and qualitatively explained network Quality of Service. Service Quality Management in the voice domain requires many combined (Service Level Agreements) between service providers and the use of protocols gnaling QoS I want to show.
In the next chapter we have discussed about the QoS, and QoS requirements for voice. Under the QoS requirements needed for the sound quality better in VoIP networks.
