vocaltec internet phone

King Fahd University of Petroleum and Minerals Computer Engineering Department COE 341 Voice Over Internet Protocol Prepared for: Dr. Radwan Abde-Aal Prepared By: Ayman Al Bassam 232101 & Amar Farouk Merah 237925 19th of November 2007 Table of Content I. Introduction…………………………………………………….1 II. Historical Background……………………..…………………1 III. How does VoIP work?.............................................................1 IV. Advantages of VoIP………………………………………….4 V. Implementation Challenges a. b. c. d. e. f. Security and Privacy……………………………………5 Reliability of Service……………………………….... …5 Delays and Jitters…………………………………….....5 Emergency Calls Routing………………………………6 Integrations with current circuit switched networks…6 Legal Issues……………………………………………...6 VI. Conclusion……………………………………………………7 V. References……………………………………………………..8 Introduction: Voice over Internet Protocol (VoIP) is one of the most revolutionary technologies ever to be brought into the world of networking and communications. Its purpose is to route analog audio signals (a voice from a person for example) to digital data that can be easily transmitted over the Internet or through any other IP-based network. Long distance calls can be made from computer to another provided they both have VoIP software on them. Basically, VoIP has turned the making of telephone calls into a whole new direction with amazing benefits such as lower costs and portability. This paper will discuss the history of VoIP, how they function, the advantages of using VoIP as a telephony service and some challenges that may occur while implementing this remarkable technology. Historical Background: VoIP dates back as far as 1973, when the early Internet was around. Analog audio signals of voice were digitalized and transmitted over this Internet as digital signals. This technology was not available to end-users till at least the 1990's. An example of a such a VoIP service was Vocaltec Internet Phone Release 4, which was introduced to the general public by 1996, and included extra services such as a voice mailbox and a caller ID feature. Vocaltec was successful at its time due to the use of real-time voice compression, which was very useful due to the low Internet connections users had at the time (limited to 28.8 kbps over a dial-up modem). The only problem with Vocaltec was the limitation of being able to talk only to other Vocaltec users. Later on in 1997 came Level 3 which dissolved that problem by implementing what they call softswitching which were designed to serve switchboards between two telephone networks, therefore removing that barrier Vocaltec had in place with their service. How Does VoIP work? The functionality of the VoIP service obviously differs almost totally from the standard traditional telephony systems. VoIP systems use packet-switching as opposed to the telephony systems' use of circuitswitching. Analog audio data is divided into packets (or chunks of data) and is then sent through many different connections in order to speed the process up. Each packet is given a destination address to know where it's going and a sequence number to allow proper and in-order merging of the packets so that they arrive in their firstly transmitted state. Moreover, VoIP works in such a way that it splits audio into samples, compresses them as much as possible so that the data is still understandable by the recipient computer. This process of compressing and de-compressing is done by CODECs, which have algorithms used to choose the best way of sampling these analog audio signals, compress them and send them over a network. At the recipient's end, another CODEC on that computer does the total reverse. Below is a simple and straightforward diagram that shows an overview of how a VoIP system basically works. VoIP also makes use of media gateways, which are used to translate multimedia communications into a digital form that can be transmitted over multiple transport protocols such as IP. These gateways can be used to connect between many different types of networks, and therefore have to use many different coding techniques and are usually imbedded with features such as echo cancellation, Dual-Tone-Multi-Frequency (DTMF) and tone sending. These gateways are controlled by media gateway controllers, which in turn control calls and signal functionality by enforcing protocols such as Media Gateway Control Protocol (MGCP) and Session Initiation Protocol (SIP). There are three different ways to use the VoIP service nowadays. This broadens the access to making phone calls over an IP-based network and does not limit the user to just one choice. These three alternatives are Analog Telephone Adaptors (ATAs), IP phones and computer-tocomputer. ATA is known to be the most simple and common way of placing VoIP calls and basically allows you to connect a normal telephone to your computer. It acts as an analog-to-digital converter which will convert the analog audio signals from your voice to a digital signal that can be sent over the Internet connection you are using. Some examples of providers of these ATAs are Vonage and AT&T CallVantage. IP phones look just like the standard traditional telephone sets, with the only physical appearance difference in the phone connector used. Normal telephones have a RJ-11 phone connector, whereas IP phones have Ethernet connectors which connect you directly through a router that will allow you to place your call over the Internet. These IP phones usually come with all the hardware and software needed to start a VoIP call, and are relatively easy to use. The third choice, computer-to-computer, is probably the easiest, most convenient and most cost-effective way to use VoIP. Software, offered by various companies at no or very low cost, is installed on both the sender and recipient parties' computers and after getting a normal headset (with both headphones and a microphone) and an Internet connection you are all set to use the services of VoIP. The only cost you may encounter is the monthly or yearly Internet subscription fee that is enforced by the Internet provider only. VoIP is becoming the new technology craze, as it requires almost nothing from an Internet user wanting to use this service. In order to get started, you will need an Internet connection, and preferably a fast one with a bandwidth of 2 Mbps (Cable, DSL, T1 and T3 are all examples). Another crucial requirement is a VoIP box, which will allow you to connect your phones all over your household to your computer which will then connect you to the Internet. This is usually provided by the VoIP service provider and may not cost too much. Along with this VoIP box, the VoIP service provider you are subscribed with should also supply you with an account that you and only you are entitled to use. This usually comes with a username and password to restrict unauthorized access by others. If you are looking for the feature of portability, you could get a Wi-Fi enabled phone, but this is not required if you are looking for just the basic needs to make a VoIP call. Advantages of VoIP: Being able to use VoIP nowadays has brought to us many benefits. The ability to engage into PC-to-PC phone call has never been better, as it allows users to communicate telephonically through a broadband connection with either DSL or cable at a very low cost and sometimes at no cost at all, provided that both computers have a VoIP service installed on them. VoIP has no geographical limit and is only restricted to having access to a broadband Internet connection, a PC with VoIP service on it and, well, the ability to speak into a microphone. Another advantage to this service is the ability to be mobile and still have access to VoIP. For example, a traveler with a broadband connection on his laptop can contact anyone that has VoIP at a very cheap rate (according to the service provided by the country he or she is in). This facilitates communication between business colleagues and the traveler if he or she is on a business trip for example. There is no need to worry about coverage, roaming service or long distance call charges anymore. “VoIP holds the promise of integrating voice communications with other technologies to create a set of customized and personalized applications,” says Keith Nissen, a Senior Analyst with In-Stat/MDR, the leading provider of actionable research, market analysis and forecasts of advanced communications services, infrastructure, end-user devices and semiconductors. “Where today’s services are associated with a connection or a device, VoIP services will be associated with the subscriber, and will be accessible from any device, anywhere, over wireline or wireless access networks.” The use of existing networks all over the world has also helped in making the service of VoIP more beneficial. Almost all countries in the world have a VoIP service provider along with their broadband Internet service. All a user needs is the VoIP service installed on his machine and he can use this service almost anywhere in the world by connecting through one of the various existing networks with almost no cost. This is also very helpful in case of large cooperate compound who already has LAN infrastructure installed. VoIP telephone can be used within the same compound instead of installing and operating a different telephone network. The ability to compress analog data has also allowed for the use of less bandwidth to transmit data. As data is made to take up less space, more can be sent on the same bandwidth, or less bandwidth could be used to send that compressed data, both of which can be benefits to the users in however one of the two ways the VoIP service has been designed. This allows for convenience and more satisfaction from end-users. Implementation challenges: As fascinating and interesting VoIP might be it also faced many challenges in it’s implementations. Some of these problems has been solved some of are not. Some of these problems and their suggested or implemented solutions are discussed below: 1. Security and privacy: while current PSTN networks are well established and have been improved over the years their secrity is fairly reasonable. However for VoIP security standards have note been set yet many of VoIP service provider does not offer any level of encryption for the data been send or recived, this means that the packets could be easily intercepted and decompressed. While compression of data can make more difficuilt to intercept VoIP calls it’s not considered as a real security measure. Real secuirity requires encryption of data. However that is easly possible because of the underlying structure of IP networks which implement encryption in many other services, Some of the ATAs uses the existing SRTP and ZRTP security standards that already available for PSTN, while other VoIP providers uses their own security measures like skype which uses an encryption that only visible to skype servers. 2. Reliability of service: While PSTN networks are considered to be very reliable for voice communication because they had the time to mature through the years, VoIP is relatively a new technology which is affected by many factors such as internet line status that sometimes fail or doesn’t function properly. Another case is when power outage accurse unlike regular phones which are powered by the phone lines provided by the telephone service provider, VoIP depends on the wall outlet for it’s power source. 3. Delays and Jitters: since VoIP service depends on transmitting data through packets, these packets could go through thousands of different routes and could arrive out of order this could result in jitters (un understandable noise) and delays of the sound which could make a call a very bad experience. One solution for this problem is the use of buffer (play-out buffers) that gathers the voice packets and send them at once upon arrival. Some delays also can be controlled by marking some voice packets as higher priority or delay sensitive. 4. Emergency calls routing: while in PTN network when an emergency number is dialed the call is routed to the nearest emergency center. However in case VoIP and because of the nature of IP networks it’s hard to tie one IP address to a specific location adding to that most ISP offer dynamic IP addresses which means that the client IP addressed is changed with each new connection. Some work around of this problem is to require a physical location registration with the VoIP service provider allowing the call to be routed automatically to the nearest emergency center. 5. Integrations with current circuit switched networks: one of the aims of VoIP service to allow communication between VoIP phone/Computer to landline/cell phone. The circuit switched network uses E.164 standards to allocate and identify phone numbers, while no such standard exist for VoIP service, some VoIP providers uses E.164 standard to assign a phone number from and to VoIP telephone while some doesn’t it is also hard to integrate between different VoIP service providers due to the lack of standardizations. 6. Legal issues: In many countries where PSTN providers are owned by the government. VoIP is not allowed or high taxes are imposed on the use of VoIP service in fear of people switching completely to VoIP services and decrease in the state income. For example in the UAE it is not allowed to use VoIP, while in India it is possible to use VoIP however it is illegal to have a VoIP gateway in India. Conclusion: While VoIP sounds like a very promising technology it is not completely facilitated and standardized to be completely dependable or to be used as a full alternative to PSTN service. However it does represent the future form of communication it also should be noted that many services can be integrated within VoIP like video calls. The market has seen recently many products related to VoIP like mobile phones that operates on both GSM and Wi- Fi or internet connection thorugh 3G networks also new products that uses WVoIP (Wlan VoIP) that operated wirelessly using Wi-Fi hotspots. With more development and as the technology advances VoIP could be the standard for telephony communications. References: 1. “How Does VoIP work?”. < http://www.voip-sol.com/how-does-voip-work/> 2. “How Does VoIP Work?” 1-3 3. Valdes, Robert. “How VoIP works?” < http://communication.howstuffworks.com/ip-telephony.htm/printable > 4. “Voice over Internet Protocol”. Wikepedia. < http://en.wikipedia.org/wiki/Voice_over_IP > 5. Schueneman, Thomas. “The Advantages and Disadvantages of using VoIP” < http://ezinearticles.com/?The-Advantages-and-Disadvantages-of-UsingVoIP&id=147921>