Prepared for Dr: Radwan Abdel-Aal. COE 341 Term report, November 2006

Transcription

1 Collage of Computer Sciences and Engineering Department Report about: Voice over Internet Protocol Prepared for Dr: Radwan Abdel-Aal COE 341 Term report, November 2006 By: Zuhair Khayyat, Ahmad Al-Sharedah, Mohammed Almohsin,

2 TABLE OF CONTENTS INTRODUCTION...1 I. ADVANTAGES OF VoIP.. 2 II. TYPES OF VoIP.3 III. HOW IT WORKS...4 a. Requirements b. Components i. Call Processing Server ii. User Devices iii. Media/VoIP Gateways iv. IP Network IV. QUALITY AND DELAY..5 a. Call Quality b. Service Quality c. Delay V. SECURITY ISSUES...6 a. Denial of Service b. Theft of Service c. Invasion of Privacy VI. DRAWBACKS AND IMPLEMENTATION CHALLENGES..7 a. Faxes b. Internet Connection c. Emergency calls d. Mobile VoIP CONCLUSION...12 REFERENCES...14

3 Voice over Internet protocol Introduction: Voice over Internet Protocol is the transport of voice over IP based data networks like WAN, MAN and LAN. In other words, it is a method for taking analog audio signals and turning them into digital data organized into packets that can be transmitted over the Internet. Due to VoIP advantages and superiority, it will be a good replacement for the traditional circuit-committed protocols of the PSTN (public switched telephone network) to make calls and any other service. However, we will discuss in this report a lot of draw backs and implementation challenges which will face the deployment of VoIP. The first implementation of transmitting voice over the network was in 1973 through Network Voice Protocol (NVP) which was invented for Advanced Research Projects Agency Network (ARPANET). In 1990 s, there were a lot of VoIP applications that faced the problem of incompatibility due to fundamental differences between different vendors. Therefore, standards, specifications and interoperability guidelines were founded in May 1996 to standardize VoIP technology, which was a consortium of major equipment vendors and technology organizations including Cisco, VocalTec, 3Com, Microsoft, USRobotics and NetSpeak. Nowadays, the VoIP forum is operating under the umbrella of international Multimedia Teleconferencing Consortium (IMTC). However in 2003, there was a public hearing, with the purpose of gathering information on advancements, innovations, and regulatory issues related to VoIP services which was announced by the Federal Communications Commission (FCC) as a VoIP Forum. Voice over Internet Protocol 1

4 VoIP nowadays is used in many companies to communicate between different sections and offices in the same building through its LAN. For example, VoIP is used as a central phone system for internal communication in Ministry of Water and electricity, which is located in Riyadh, by CISCO. Moreover, many other companies can provide VoIP either as a central system in a company or as a service providing phone line to call any were any time in the future such as Vonage, AT&T, CallVantage and Verizon VoiceWing. 1. advantages of VoIP: The current Existing PSTN uses reliable and inefficient method, which is circuit switching protocol, that establishes a direct detected full duplex line between the two parties. Normal conversation, which takes about 10 minutes, will transmit 10,560 KB were some times in most conversations there is dead air for seconds at a time were neither party is talking. On the other hand, VoIP uses packet switching which packets contain useful information and they travel through a complex network along thousands of possible paths. Packet switching frees up the two computers communicating so that they can accept information from any other computer while it allows the network to route the packets along the least congested and cheapest lines. In contrast to PSTN, in a 10 minute call using VoIP, will result in a transmutation about 2880 KB, which is 3.6 times less data than the PSTN. As a result, there will be a huge difference in cost of service between VoIP and PSTN. In contrast to PSTN, some calls using VoIP will be free of charge while other calls will cost only the charge of subscription. Moreover, any available service over the internet could be integrated with VoIP including video and file exchange while the call could be highly encrypted for any security needs. Another advantage of IP telephony that the call can be made or received Voice over Internet Protocol 2

5 anywhere in the world while there is a connection of either WiFi or WiMAX. There are also many free services which require extra charge in normal phone companies including: caller ID, call waiting, call transfer,repeat dial,return call,three-way calling. Also, there are advanced call-filtering options available using caller ID information to allow you make a choice about how calls are Forwarded to a particular number, send the call directly to voic and give the caller a busy signal. 2. Types Of VoIP: There are three types of VoIP services to communicate between two VoIP nodes, which are computer-to-computer, IP phones and ATA. Computer-to-computer is the easiest way to communicate using VoIP which is usually free and requires only an internet connection and software, i.e. Skype and yahoo messenger. In contrast, IP phones VoIP uses a special phone, which contains RJ-45 Ethernet connector, while special equipments and service provider are needed. However, ATA is the simplest and most common way to use VoIP using an ATA (analog telephone adaptor) that allows connecting a standard phone to a computer. This type of VoIP requires a service provider and special software to conduct phone calls. On the other hand, the communication between VoIP to PSTN requires a special services such as DID (Direct Inward Dialing) and access numbers. DID connect the caller directly to the VoIP user with a monthly fee and sometimes it charges only for calls to PSTN. In contrast to DID, access number require extension number of the VoIP user and it charges only as a local call to the PSTN. Voice over Internet Protocol 3

6 3. How it works 3.1 Requirements: The most interesting thing about VoIP is that there is not one way to place a call. Also, one of the VoIP service is Computer-to-Computer connection. In this service all you need is just the software, a microphone, speakers, a sound card and an Internet connection, better to be a fast one like you would get through a cable or DSL modem. 3.2 Components: VoIP network has four major components. They are call processing server, user devices, media/voip gateways and IP Network Call Processing Server: It is also known as IP/PBX controls VoIP connections. This service allows various configurations to be deployed from a single server to a server farm. These kinds of deployments are based on very standard hardware that is running specialist software applications. These call processing servers are available either on router platforms or as an appliance User Devices This component may be outer or discrete devices, such as hard phones, soft phone. Also, VoIP phones include PCs and desktop while VoIP mobile include laptop computers for example Media/VoIP Gateways Gatekeepers are another name for VoIP gateways. They were used for call admission and control and also for bandwidth management. VoIP packets from analogue voice Voice over Internet Protocol 4

7 signal using CODECs is done by media gateway as main functions for this component. Gateway functionality can handle many features such as compression, echo cancellation, silence suppression and traffic management IP Network Elements of VoIP networks are connected by IP network. Quality service must be repaired because the sensitivity of VoIP traffic to delay. To avoid any affect for VoIP traffic by other net work traffic we should use Class of Service (CoS). 4. Quality and Delay: 4.1 Call Quality: This kind of quality depends on two things. One is the provider you use for VoIP service. The other one is bandwidth, also called quality, of the internet connection you use. Computer-to-Computer calls are said to be excellent if there is reasonable bandwidth exist. Before spending your money you can get a free trial form the VoIP provider and you also can have a lot of service reviews. In most cases 90% of call quality is as good as that of regular telephones. 4.2 Service Quality: Jitter, delay, packet loss, data errors, bandwidth fluctuations and dropped connections can susceptible transformation of data through the data networks. However some of these bad effects can be handled by IP but latency and jitter have major effect on voice and video over IP. However, The PSTN allows fast call setup times, a robust feature set, and a sophisticated billing and settlement system. This has created expectations of QoS for VoIP calls, which should be at least as easy and as good as PBX or PSTN calls (sometimes referred to Voice over Internet Protocol 5

8 as toll quality or feature parity ). Voice quality, network performance, call control and interoperability are covered by the QoS. There are a large number of technologies that can be chosen to provide QoS support such as Diffserv, RSVP, MPLS and even ATM. 4.3 Delay: Number of quality problems can be introduced by digitizing, because voice is analogue and has a continuous nature. The time a packet takes to travel from its point of origin to its destination is called the Packet Delay. A number of technical issues can cause delay. This technical issue includes call distance and routing, incompatible CODECs, bandwidth reliability and disparity, network congestion, and data errors. Echo becomes major problem when the round-trip delay is more than 50 milliseconds. This is done by echo and talker overlap. Also, most calls can control a delay of 150 milliseconds or less. Talker overlap becomes problematic with delay of 250 milliseconds or more and any delay above 400 milliseconds is untenable. 5. Security Issues: A VoIP Next-Generation network is much more susceptible to security attacks and must address three key security issues. They are denial of service, theft of service and invasion of privacy. 6.1 Denial of Service: Accessing the features and services offered by any network from legitimate users of that network. In the PSTN it is not easy to use the denial of service attacks but all too common in IP networks. There is a lot of service's denial in any complex network. Sending false signaling messages so that a call agent is Voice over Internet Protocol 6

9 fooled into believing that a party has gone on-hook is an example of that denial of services. 6.2 Theft of Service: Simply it is where the user wants to use without paying for it. Here we have two kinds of thefts of service. Subscriber fraud is the most common form in the current PSTN, where a subscriber sets up an account with a service provider using false billing information an example for that is stolen credit card. The other form is the theft is more technical to get that service free. 6.3 Invasion of Privacy: Mainly no body can eavesdrop on any connection between any two parties. This achieves by the PSTN by physical security mechanisms. This kind of security is done as the wire from a subscriber s home is only connected to the local exchange or digital loop carrier and cannot easily be accessed. In case of shared media there is an eavesdropping even if we use encryption in particular cable or wireless networks. However it is important to note that there is no one size fits all approach to security for VoIP, for example networks that use an ATM based DSL access are fundamentally point to point networks and for these networks encryption is unnecessary provided that the core network is suitably secured. 6. Drawbacks and implementation challenges: VoIP technology still has a few shortcomings that have led some to believe that it is not ready for widespread deployment, and because UDP does not provide a mechanism to ensure that data packets are delivered in sequential order, or provide Quality of Service guarantees, VoIP implementations face problems dealing with latency and jitter. This is especially true when satellite circuits are involved, due to long round trip propagation delay (400 Voice over Internet Protocol 7

10 milliseconds to 600 milliseconds for geostationary satellite). The receiving node must restructure IP packets that may be out of order, delayed or missing, while ensuring that the audio stream maintains a proper time consistency. This functionality is usually accomplished by means of a jitter buffer. 6.1 Faxes: one of drawbacks and challenges is the difficulty in sending faxes due to software and networking restraints in most home systems. However, an effort is underway to define an alternate IP-based solution for delivering Fax-over-IP, namely the T.38 protocol. Another possible solution to overcome the drawback is to treat the fax system as a message switching system which does not need real time data transmission. The end system can completely buffer the incoming fax data before displaying or printing the fax image. 6.2 Internet Connection: Another one of drawbacks and challenges of VoIP service is its frequent reliance upon another separate service - an internet connection. The quality and overall reliability of the phone connection is entirely reliant upon the quality, reliability, and speed of the internet connection which it is using. Shortcomings with internet connections and Internet Service Providers (ISPs) can cause a lot of grief with VoIP calls. Higher overall network latencies can lead to significantly reduced call quality and cause certain problems such as echoing. VoIP isn't entirely reliant upon internet connections, however. VoIP systems can also utilize regular telephone lines and business-grade connections like T1's for voice service. A few business VoIP Providers offer dedicated point-to-point T1 connections, thereby not relying on an internet connection for service. Although residential VoIP service typically uses only an internet connection, business-grade VoIP service can use a Voice over Internet Protocol 8

11 variety of connection methods to provide ongoing phone service. Many VoIP users still maintain a traditional analog voice line (business line) which allows them to utilize a traditional fax machine when needed and can also be used to call 911 services if you have an analog phone on the fax machine as well. 6.3 Emergency calls: One of the biggest drawbacks is the nature of IP makes it difficult to geographically locate network users. Emergency calls, therefore, cannot easily be routed to a nearby call center, and are impossible on some VoIP systems. Moreover, in the event that the caller is unable to give an address, emergency services may be unable to locate them in any other way. Following the lead of mobile phone operators, several VoIP carriers are already implementing a technical work-around. For instance, one large VoIP carrier requires the registration of the physical address the VoIP line will be used at. When you dial the emergency number for your country, they will route it to the appropriate local system. They also maintain their own emergency call center that will take non-routable emergency calls (made, for example, from a software based service that is not tied to any particular physical location) and then will manually route your call once learning your physical location. The United States government had set a deadline, requiring VoIP carriers to implement E911; however, the deadline is being appealed by several of the leading VoIP companies. This is a different situation with IPBX systems, where these corporate systems often have full E911 capabilities built into the system. Voice over Internet Protocol 9

12 6.4 Mobile VoIP: Mobile VoIP or 'mobile voice over Internet Protocol' is an extension of the voice over IP technology and service. It puts wings on the classic approach of VoIP. Mobile phones have achieved nearly complete market penetration, and many people are giving up landlines and using mobiles exclusively. Given this situation, it is not entirely clear whether there would be a significant higher demand for VoIP among consumers until either a public or community wireless networks have similar geographical coverage to cellular networks (thereby enabling mobile VoIP phones, so called WiFi phones). VoIP is implemented over legacy 3G networks. However, "dual mode" handsets, which allow for the seamless handover between a cellular network and a WiFi network, are expected to help VoIP become more popular. Mobile VoIP is more than Voice over WiFi or VoWiFi. Using any broadband IP-capable wireless network connection mobile VoIP will be an application over other networks such as EVDO rev A (which is synchronously high speed - both high speed up and down), HSDPA or potentially WiMax. Mobile VoIP will enable further economic and mobility tradeoffs. For example, Voice over WiFi offers free service but is only available within the coverage area of the WiFi Access Point. High speed services from mobile operators using EVDO rev A or HSPDA with probably have better audio quality and capabilities for metropolitan-wide coverage including fast handoffs from mobile base station to another, yet it will cost more than the typical WiFi-based VoIP service. By mid-2006, there are an estimated 70 million users of Skype - a PC to PC service for voice communications over the Internet Protocol and some 20 million users of gateway-togateway voice over IP services such as Vonage, and there are a Voice over Internet Protocol 10

13 billion users of mobile phone users around the world. Each of the endpoints in any VoIP service is in various ways, a computer: - The gateway that Vonage users plug their home phones into. - The PC (of course) that runs the Skype client. - Depending on the capabilities of the specific mobile model, the mobile phone in your pocket. Mobile VoIP will become an important service in the coming years as device manufacturers exploit more powerful processors and less costly memory to meet the users' needs for ever-more 'power in their pocket'. Smart phones in mid-2006 are capable of sending and receiving , browse the web (albeit at low rates) and in some cases watch TV. The challenge for the mobile operator industry is to deliver the benefits and innovations of IP without losing control of the network service. Users like the Internet to be free and high speed without extra charges for visiting specific sites versus other sites. Delivering mobile VoIP is a service that challenges the most valuable service in the telecommunications industry - voice - and threatens (or promises, depending on your views) the pace of innovation in the global communications industry. Mobile VoIP took a significant step forward in the summer of 2006 when Nokia included not only a SIP (Session Initiation Protocol) stack but a VoIP client in their new E-series dual-mode WiFi handsets (E60, E61, E70). The E-series handsets are aimed at enterprise buyers, and significantly Nokia have announced their intention to do the same thing for consumer handsets by launching the N80 Internet edition in November In theory these handsets only require the settings to be populated into the user interface, however this process requires nearly 200 key clicks so very few unsupported Voice over Internet Protocol 11

14 users succeed in using the handsets for VoIP. The first mobile VoIP operator to launch on these handsets is the UK-based Truphone, using an OTA (Over The Air) provisioning method: users send a text to the relevant Truphone number in each country, which sends a text back containing a link which then downloads and runs a provisioning wizard. Conclusion: Previously, the challenges of security, quality and delay, types of VoIP, and drawbacks have been discussed in relation to the implementation of VoIP. Despite the technical complexities that may exist, it is possible to purchase wireless VoIP devices that provide excellent voice quality in today s market. These offerings, often requiring vendor specific adjunct components, are being deployed in an increasing number in commercial and enterprise environments. As technology advances, so do the demands and requirements of those customers that want to integrate such technologies into their corporate infrastructures. As with most things in life -- there are many changes on the horizon for wireless VoIP products. In this report, we tried to look into the present and future of VoIP and identify some key elements of the VoIP. VoIP has started a new revolution in the history of Internet Telephony. With more software companies embracing VoIP, it is recreating itself with the advent of the new technology. It is believed that future of VoIP is VoIP 2.0, which will focus on services instead of cut-rate pricing. Though companies like Google, Skype and Microsoft are offering new services now, the day is not far when every company will be forced to charge for this service after adding new features and technologies. VoIP 2.0 is the latest version of VoIP which will allow the users to advantage of more flexibility, customization and powerful features. It is being Voice over Internet Protocol 12

15 planned to introduce more advance features rather than the simple conferencing feature. It will be the next phase of VoIP. VoIP 2.0 is the theme of Internet Telephony Conference & Expo to be held this October in Los Angeles. Using VoIP 2.0 may prove to be more productive, efficient and profitable. Voice over Internet Protocol 13

16 References: 1. Chris Roberts. Voice over internet protocol. Centre for Critical Infrastructure Protection. March 2005 < (8-Nov-06). 2. Paul Drew, and Chris Gallon. Next-Generation VoIP Network Architecture MSF Technical Report. March, < (10-Nov-06). 3. Robert Valdes How VoIP works. How stuff works. < (9- Nov-06). 4. Voice over Internet protocol Consumer Sheet. July 15, < (5-Nov-06). 5. Voice over Internet Protocol Wikipedia website. 8 November < (9-Nov-06). 6. Eric B. Parizo. Avoiding a VoIP security 'judgment day'. VOIP News. 01 Mar < SearchEnterpriseVoice.com> (10- Nov-06). 7. Jeff Bertolucci. Internet Phones Call on Wi-Fi. PC World. July 27, < page,1/article.html?rss=rss> (10-Nov-06). 8. VOIP Information. < (10-Nov-06). 9. IEEE website. < (10-Nov-06). Voice over Internet Protocol 14