Seminar OnVoIP(Voice Over Internet Protocol) Presented by: Ankita Kankani 8th Semester, IT
Talk Overview : Introduction VoIP- Packet Switching Major Concerns of VoIP CODEC Quality of Service Advantages of VoIP Future Concerns of VoIP Conclusion Refrences
Introduction Voice over Internet Protocol (VoIP) is a technology thatenables one to make and receive phone calls through theInternet instead of using the traditional analog PSTN (PublicSwitched Telephone Network) lines. The voice-over-Internet protocol (VoIP) technology allowsvoice information to pass over IP data networks. VoIP converts the voice signal from your telephone into adigital signal that travels over the Internet then converts it backat the other end so you can speak to anyone with a regular phonenumber.
Basic Flow Of VoIP Network Signaling: Signaling in a VoIP network is accomplishedby the exchange of datagram messages between thecomponents. The format of these messages is covered bythe standard datalink layer protocols. Database service : Database services are a way to locatean endpoint and translate the addressing that twonetworks use. Call connect and disconnect (bearer control) : Theconnection of a call is made by two endpoints openingcommunication sessions between each other. CODEC operations : Voice communication isanalogue, while data networking is digital. Analoguewaveforms are converted into digital information by usinga coder-decoder (CODEC).
Flavors of VoIPATA :• Connects a standard phone to a computer or an Internet connection for use with VoIP.• The ATA is an analog-to-digital converter.IP Phones :• connect directly to a router and have all the hardware and software necessary right onboard to handle the IP call.Computer-to-Computer :• There are several companies offering free or very low- cost software that you can use for this type of VoIP.• All you need is the software, a microphone, speakers, a sound card and an Internet connection.
How Does VoIP Work ??
VoIP converts the voice signal from your telephone into adigital signal that travels over the Internet. If you are calling a regular phone number, the signal isthen converted back at the other end. Internet Voice can allow you to make a call directly from apersonal computer. If you make a call using a phone with an adaptor, you’ll beable to dial just as you always have.
Packet Switching The users voice (or fax) is converted into a digitalsignal, compressed, and broken down into a series ofpackets. The packets are then transported over private or publicIP networks and reassembled and decoded on thereceiving side. At the receiving end, the re-assembled packets arrive asa normal sounding voice call. Packet switching is very efficient. It lets the networkroute the packets along the least congested and cheapestlines. It also frees up the two computers communicatingwith each other so that they can accept information fromother computers, as well.
A Typical VoIP Network VoIP data travels over the networks in packets. In VoIP digitized voice is bundled into IP packets and sent out into the network for delivery. Routers, switches, and other network equipment direct the packets to their destination IP address. This mode is called packet switched telephony. The transport of voice packets is affected by several factors, such as the amount of bandwidth available in the network connection, the delay that the packet experiences, and any packet loss or corruption that occurs. The ability of the network to deliver the voice packets quickly and consistently is referred to as Quality of Service (QoS).
Major Concerns Of VoIP Gateways: The gateways are the devices that communicate between the telephone signals and the IP endpoint. Gatekeepers: gatekeeper knows how many users are connected and where they are located. The collection of a gatekeeper and its registered endpoints is called as a zone. IP Telephones: These are devices, which replace the existing telephones by providing enhanced services suited to VOIP. PC Software phones: This arrangement consists of a microphone connected to a PC interfaced by a card and running software, which permits voice and multimedia transfer over the Internet. Microsoft NetMeeting, Skype and Viber are an example.
VoIP CODECS A codec which stands for coder-decoder, converts an audio signal into compressed digital form for transmission and then back into an uncompressed audio signal for replay. Its the essence of VoIP. Codecs sample the audio signal several thousand times per second. Summary of available codecs:G.711 64 kbpsG.721 32 kbpsG.728 16 kbpsG.729 8 kbps VoIP software processes and routes the calls.
VoIP QoS (Quality Of Services) Issues Quality of Service is essential for the success of VoIP. The human ear is extremely sensitive to even minor changes in an audio signal. Loss of quality occurs when the voice packets are transferred over the inherently unreliable packet-based networks.Some methods to enhance the QoS achieved in VoIP are:Classification of Service: Using the TOS bits in the IP header to set a priority for the voice packet.Tagging the packets with labels and using the labels to decide the route. Voice packets can be routed over less congested networks.
Delay : Delay causes two problems: echo and talkeroverlap. Echo is caused by the signal reflections of thespeakers voice from the farend telephone quipmentback into the speakers ear. Jitter : The delay problem is compounded by theneed to remove jitter, a variable interpacket timingcaused by the network a packet traverses. Lost-Packet Compensation : Lost packets can bean even more severe problem, depending on the typeof packet network that is being used. Because IPnetworks do not guarantee service, they will usuallyexhibit a much higher incidence. Echo Compensation : These reflections of thespeakers voice are heard in the speakers ear. Echo ispresent even in a conventional circuit-switchedtelephone network.
Advantages of Using VoIP With VoIP mechanism you can talk all the time with every person you want. (the needed is that other person is also connected to Internet at the same time) Integration of Voice and Data : The integration of voice and data traffic will be demanded by multi application software. The inevitable evolution will be web servers capable of interacting with voice, data and images. Simplification : An integrated infra structure that supports all forms of communication allows more standardization and lesser equipment management. The result is a fault tolerant design.
Continued…. Network Efficiency : The integration of voice anddata effectively fills up the data communicationchannels efficiently, thus providing band widthconsolidation. The idea is to move away from the TDMschema where in the user is given bandwidth when heis not talking. Cost reduction : The Public Switched TelephoneNetworks toll services can be bypassed using theInternet backbone, which means slash in prices of thelong distance calls.
Future of VoIP Telephony Several factors will influence future developments in VoIP products and services. Currently, the most promising areas for VoIP are corporate intranets and commercial extranets. Their IP– based infrastructures enable operators to control who can—and cannot—use the network. Another influential element in the ongoing Internet- telephony evolution is the VoIP gateway. As these gateways evolve from PC–based platforms to robust embedded systems, each will be able to handle hundreds of simultaneous calls.
Continued… Commercial extranets, based on conservatively engineered IPnetworks, will deliver VoIP and facsimile over Internet protocol(FAXoIP) services to the general public. Today’s Advanced Intelligent Network (AIN) provides manyuseful features common to callers today. These features includeCaller ID, Voice Mail, Call Waiting, Pre-and-post paid callingcards, 911, Call Blocking.
Reliability, Availability, Support - Some form of reliablecommunications is considered a life-safety issue.
Interconnected VoIP ServiceInterconnected VoIP service allows you to make and receivecalls to and from traditional phone numbers using an Internetconnection, possibly a high-speed (broadband) Internetconnection, such as Digital Subscriber Line (DSL), cablemodem, or wireless broadband. It can be used in place of traditional phone service.Typically, interconnected VoIP technology works by eitherplacing an adapter between a traditional phone and Internetconnection, or by using a special VoIP phone that connectsdirectly to your computer or Internet connection. While you may choose to use interconnected VoIP servicefrom a single location, like a residence, some interconnectedVoIP services can be used wherever you travel, as long as abroadband Internet connection is available.
Conclusion VoIP technology offers broadband services and theintegration of voice and data at all levels. One key factorthat is driving the VoIP application development anddeployment is reduced voice service charges. In addition to cost advantages, VoIP services havecompelling technical advantages over circuit switching.Moreover, VoIP is suitable for computer telephonyintegration and other next generation applications. A VoIP network can centralize much of its intelligenceso the management of the network can also becentralized.
Continued…. A service provider can centralize the networkoperations and billing. Enterprises can also deploy anIP telephony system. VoIP will no longer be a service but a technologythat is utilized in an application that may run on acomputer, a PDA or other information andcommunication appliance. VoIP is growing fast. The very knowledge of theapplications of this technology is enough for users andmanufacturers to flock towards it. It is ideal forcomputer based communications and at the same timebringing down the cost of multimedia transfer.