VOICE OVER INTERNET PROTOCOL SEMINAR

VOICE OVER INTERNET PROTOCOL

CONTENTS

¨    INTRODUCTION

¨    PROTOCOL

¨    ADOPTION

¨    ADVANTAGES

¨    CHALLENGES

¨    LEGAL ISSUES

¨    CONCLUSION

¨    REFERENCES

INTRODUCTION

                         Voice over Internet Protocol (VoIP) is a form of communication that allows you to make phone calls over a broadband internet connection instead of typical analog telephone lines. Basic VoIP access usually allows you to call others who are also receiving calls over the internet. Interconnected VoIP services also allow you to make and receive calls to and from traditional landline numbers, usually for a service fee. Some VoIP services require a computer or a dedicated VoIP phone, while others allow you to use your landline phone to place VoIP calls through a special adapter.

                         VoIP is becoming an attractive communications option for consumers. Given the trend towards lower fees for basic broadband service and the brisk adoption of even faster internet offerings, VoIP usage should only gain popularity with time. However, as VoIP usage increases, so will the potential threats to the typical user. While VoIP vulnerabilities are typically similar to the ones users face on the internet, new threats, scams, and attacks unique to IP telephony are now emerging.

                   Voice over Internet Protocol commonly refers to the communication protocols, technologies, methodologies, and transmission techniques involved in the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. Other terms commonly associated with VoIP are IP telephony, Internet telephony, voice over broadband (VoBB), broadband telephony, IP communications, and broadband phone. Internet telephony refers to communications services —voice, fax, SMS, and/or voice-messaging applications— that are transported via the Internet, rather than the public switched telephone network (PSTN). The steps involved in originating a VoIP telephone call are signaling and media channel setup, digitization of the analog voice signal, encoding, packetization, and transmission as Internet Protocol (IP) packets over a packet-switched network.

Voice over IP (VoIP) can facilitate tasks and deliver services that might be cumbersome or costly to implement when using traditional PSTN:

• More than one phone call can be transmitted on the same broadband phone line. This way, voice over IP can facilitate the addition of telephone lines to businesses.
• Features that are usually charged extra by telecommunication companies, such as call forwarding, caller ID or automatic redialing, are simple with voice over IP technology.
• Unified communications are secured with voice over IP technology, as it allows integration with other services available on the internet such as video conversation, messaging, etc.

PROTOCOL

• H.323
• Media Gateway Control Protocol (MGCP)
• Session Initiation Protocol (SIP)
• Real-time Transport Protocol (RTP)
• Session Description Protocol (SDP)
• Inter-Asterisk exchange (IAX)

                            The H.323 protocol was one of the first VoIP protocols that found widespread implementation for long-distance traffic, as well as local area network services. However, since the development of newer, less complex protocols such as MGCP and SIP, H.323 deployments are increasingly limited to carrying existing long-haul network traffic. In particular, the Session Initiation Protocol (SIP) has gained widespread VoIP market penetration.

                 A notable proprietary implementation is the Skype protocol, which is in part based on the principles of peer-to-peer (P2P) networking.

ADOPTION

Consumer market

Example of residential network including VoIP

                    A major development that started in 2004 was the introduction of mass-market VoIP services that utilize existing broadband Internet access, by which subscribers place and receive telephone calls in much the same manner as they would via the public switched telephone network (PSTN). Full-service VoIP phone companies provide inbound and outbound service with Direct Inbound Dialing. Many offer unlimited domestic calling for a flat monthly subscription fee. This sometimes includes international calls to certain countries. Phone calls between subscribers of the same provider are usually free when flat-fee service is not available A VoIP phone is necessary to connect to a VoIP service provider. This can be implemented in several ways:

• Dedicated VoIP phones connect directly to the IP network using technologies such as wired Ethernet or wireless Wi-Fi. They are typically designed in the style of traditional digital business telephones.
• An analog telephone adapter is a device that connects to the network and implements the electronics and firmware to operate a conventional analog telephone attached through a modular phone jack. Some residential Internet gateways and cable modems have this function built in.
• A soft phone is application software installed on a networked computer that is equipped with a microphone and speaker, or headset. The application typically presents a dial pad and display field to the user to operate the application by mouse clicks or keyboard input.

PSTN and mobile network providers

                         It is becoming increasingly common for telecommunications providers to use VoIP telephony over dedicated and public IP networks to connect switching centers and to interconnect with other telephony network providers; this is often referred to as "IP backhaul".Smartphones and Wi-Fi enabled mobile phones may have SIP clients built into the firmware or available as an application download.

Corporate use

                         Because of the bandwidth efficiency and low costs that VoIP technology can provide, businesses are migrating from traditional copper-wire telephone systems to VoIP systems to reduce their monthly phone costs. In 2008, 80% of all new PBX lines installed internationally were VoIP. VoIP solutions aimed at businesses have evolved into unified communications services that treat all communications—phone calls, faxes, voice mail, e-mail, Web conferences and more—as discrete units that can all be delivered via any means and to any handset, including cell phones. Two kinds of competitors are competing in this space: one set is focused on VoIP for medium to large enterprises, while another is targeting the small-to-medium business (SMB) market. VoIP allows both voice and data communications to be run over a single network, which can significantly reduce infrastructure costs.

ADVANTAGES

                        There are several advantages to using Voice over IP. The biggest single advantage VoIP has over standard telephone systems is cost. In addition, international calls using VoIP are usually very inexpensive. One other advantage, which will become much more pronounced as VoIP use climbs, calls between VoIP users are usually free. Using services such as TrueVoIP, subscribers can call one another at no cost to either party.

v Operational cost

·                    VoIP can be a benefit for reducing communication and infrastructure costs. Examples include:

·                    Routing phone calls over existing data networks to avoid the need for separate voice and data networks.

·              The ability to transmit more than one telephone call over a single broadband connection.

·                    Secure calls using standardized protocols (such as Secure Real-time Transport Protocol). Most of the difficulties of creating a secure telephone connection over traditional phone lines, such as digitizing and digital transmission, are already in place with VoIP. It is only necessary to encrypt and authenticate the existing data stream.

v Portability

CHALLENGES

Quality of service

                               Communication on the IP network is inherently less reliable in contrast to the circuit-switched public telephone network, as it does not provide a network-based mechanism to ensure that data packets are not lost, and are delivered in sequential order. It is a best-effort network without fundamental Quality of Service (QoS) guarantees. Therefore, VoIP implementations may face problems mitigating latency and jitter. By default, network routers handle traffic on a first-come, first-served basis. Network routers on high volume traffic links may introduce latency that exceeds permissible thresholds for VoIP. Fixed delays cannot be controlled, as they are caused by the physical distance the packets travel; however, latency can be minimized by marking voice packets as being delay-sensitive with methods such as DiffServ.

Layer-2 quality of service

             A number of protocols that deal with the data link layer and physical layer include quality-of-service mechanisms that can be used to ensure that applications like VoIP work well even in congested scenarios. Some examples include:

• IEEE 802.11e is an approved amendment to the IEEE 802.11 standard that defines a set of quality-of-service enhancements for wireless LAN applications through modifications to the Media Access Control (MAC) layer. The standard is considered of critical importance for delay-sensitive applications, such as voice over wireless IP.
• IEEE 802.1p defines 8 different classes of service (including one dedicated to voice) for traffic on layer-2 wired Ethernet.
• The ITU-T G.hn standard, which provides a way to create a high-speed (up to 1 gigabit per second) Local area network using existing home wiring (power lines, phone lines and coaxial cables). G.hn provides QoS by means of "Contention-Free Transmission Opportunities" (CFTXOPs) which are allocated to flows (such as a VoIP call) which require QoS and which have negotiated a "contract" with the network controllers.

Susceptibility to power failure

                  Telephones for traditional residential analog service are usually connected directly to telephone company phone lines which provide direct current to power most basic analog handsets independently of locally available power.

                   IP Phones and VoIP telephone adapters connect to routers or cable modems which typically depend on the availability of mains electricity or locally generated power.^[20] Some VoIP service providers use customer premises equipment (e.g., cable modems) with battery-backed power supplies to assure uninterrupted service for up to several hours in case of local power failures. Such battery-backed devices typically are designed for use with analog handsets.

                        Some VoIP service providers implement services to route calls to other telephone services of the subscriber, such a cellular phone, in the event that the customer's network device is inaccessible to terminate the call.

                       The susceptibility of phone service to power failures is a common problem even with traditional analog service in areas where many customers purchase modern telephone units that operate with wireless handsets to a base station, or that have other modern phone features, such as built-in voicemail or phone book features.

Emergency calls

                        The nature of IP makes it difficult to locate network users geographically. Emergency calls, therefore, cannot easily be routed to a nearby call center. Sometimes, VoIP systems may route emergency calls to a non-emergency phone line at the intended department; in the United States, at least one major police department has strongly objected to this practice as potentially endangering the public. A fixed line phone has a direct relationship between a telephone number and a physical location. If an emergency call comes from that number, then the physical location is known.

Lack of redundancy

                      The historical separation of IP networks and the PSTN provided redundancy when no portion of a call was routed over IP network. An IP network outage would not necessarily mean that a voice communication outage would occur simultaneously, allowing phone calls to be made during IP network outages. When telephone service relies on IP network infrastructure such as the Internet, a network failure can isolate users from all telephony communication, including Enhanced 911 and equivalent services in other locales.

Number portability                                                                     

                            Local number portability (LNP) and Mobile number portability (MNP) also impact VoIP business. In November 2007, the Federal Communications Commission in the United States released an order extending number portability obligations to interconnected VoIP providers and carriers that support VoIP providers. Number portability is a service that allows a subscriber to select a new telephone carrier without requiring a new number to be issued. Typically, it is the responsibility of the former carrier to "map" the old number to the undisclosed number assigned by the new carrier. This is achieved by maintaining a database of numbers. A dialed number is initially received by the original carrier and quickly rerouted to the new carrier. Multiple porting references must be maintained even if the subscriber returns to the original carrier. The FCC mandates carrier compliance with these consumer-protection stipulations.

PSTN integration

                              E.164 is a global FGFnumbering standard for both the PSTN and PLMN. Most VoIP implementations support E.164 to allow calls to be routed to and from VoIP subscribers and the PSTN/PLMN.VoIP implementations can also allow other identification techniques to be used. For example, Skype allows subscribers to choose "Skype names" (usernames) whereas SIP implementations can use Uris similar to email addresses. Often VoIP implementations employ methods of translating non-E.164 identifiers to E.164 numbers and vice-versa, such as the Skype-In service provided by Skype and the ENUM service in IMS and SIP.

Security                

                         VoIP telephone systems are susceptible to attacks as are any Internet-connected devices. This means that hackers who know about these vulnerabilities (such as insecure passwords) can institute denial-of-service attacks, harvest customer data, record conversations and break into voice mailboxes. Another challenge is routing VoIP traffic through firewalls and network address translators. Private Session Border Controllers are used along with firewalls to enable VoIP calls to and from protected networks. For example, Skype uses a proprietary protocol to route calls through other Skype peers on the network, allowing it to traverse symmetric NATs and firewalls. Other methods to traverse NATs involve using protocols such as STUN or Interactive Connectivity Establishment (ICE).

 

Securing VoIP

                      To prevent the above security concerns government and military organizations are using voice over secure IP (VoSIP), secure voice over IP (SVoIP), and secure voice over secure IP (SVoSIP) to protect confidential and classified VoIP communications. Secure voice over secure IP is accomplished by encrypting VoIP with protocols such as SRTP or ZRTP. Secure voice over IP is accomplished by using Type 1 encryption on a classified network, like SIPRNet. Public Secure VoIP is also available with free GNU programs and in many popular commercial VoIP programs via libraries such as ZRTP.

Caller ID

                  Caller ID support among VoIP providers varies, but is provided by the majority of VoIP providers.Many VoIP carriers allow callers to configure arbitrary caller ID information, thus permitting spoofing attacks. Business-grade VoIP equipment and software often makes it easy to modify caller ID information, providing many businesses great flexibility.  The Truth in Caller ID Act became law in on December 22, 2010. This bill proposes to make it a crime in the United States to "knowingly transmit misleading or inaccurate caller identification information with the intent to defraud, cause harm, or wrongfully obtain anything of value ..." Rules implementing the law were adopted by the Federal Communications Commission on June 20, 2011.

Compatibility with traditional analog telephone sets

                    Some analog telephone adapters do not decode pulse dialing from older phones. They may only work with push-button telephones using the touch-tone system. The VoIP user may use a pulse-to-tone converter, if needed.

Fax handling

                      Support for sending faxes over VoIP implementations is still limited. The existing voice codecs are not designed for fax transmission; they are designed to digitize an analog representation of a human voice efficiently. However, the inefficiency of digitizing an analog representation (modem signal) of a digital representation (a document image) of analog data (an original document) more than negates any bandwidth advantage of VoIP. In other words, the fax "sounds" simply do not fit in the VoIP channel. An alternative IP-based solution for delivering fax-over-IP called T.38 is available. Sending faxes using VoIP is sometimes referred to as FoIP, or Fax over IP.

 

Support for other telephony devices

                          Another challenge for VoIP implementations is the proper handling of outgoing calls from other telephony devices such as digital video recorders, satellite television receivers, alarm systems, conventional modems and other similar devices that depend on access to a PSTN telephone line for some or all of their functionality.

These types of calls sometimes complete without any problems, but in other cases they fail. If VoIP and cellular substitution becomes very popular, some ancillary equipment makers may be forced to redesign equipment, because it would no longer be possible to assume a conventional PSTN telephone line would be available in consumer's homes.

LEGAL ISSUES

                      As the popularity of VoIP grows, governments are becoming more interested in regulating VoIP in a manner similar to PSTN services.

Another legal issue that the US Congress is debating concerns changes to the Foreign Intelligence Surveillance Act. The issue in question is calls between Americans and foreigners. The National Security Agency (NSA) is not authorized to tap Americans' conversations without a warrant—but the Internet, and specifically VoIP does not draw as clear a line to the location of a caller or a call's recipient as the traditional phone system does. As VoIP's low cost and flexibility convinces more and more organizations to adopt the technology, the surveillance for law enforcement agencies becomes more difficult. VoIP technology has also increased security concerns because VoIP and similar technologies have made it more difficult for the government to determine where a target is physically located when communications are being intercepted, and that creates a whole set of new legal challenges.

In the US, the Federal Communications Commission now requires all interconnected VoIP service providers to comply with requirements comparable to those for traditional telecommunications service providers. VoIP operators in the US are required to support local number portability; make service accessible to people with disabilities; pay regulatory fees, universal service contributions, and other mandated payments; and enable law enforcement authorities to conduct surveillance pursuant to the Communications Assistance for Law Enforcement Act (CALEA). "Interconnected" VoIP operators also must provide Enhanced 911 service, disclose any limitations on their E-911 functionality to their consumers, and obtain affirmative acknowledgements of these disclosures from all consumers. VoIP operators also receive the benefit of certain US telecommunications regulations, including an entitlement to interconnection and exchange of traffic with incumbent local exchange carriers via wholesale carriers. Providers of "nomadic" VoIP service—those who are unable to determine the location of their users—are exempt from state telecommunications regulation.

Historical milestones

• 1973: Network Voice Protocol (NVP) developed by Danny Cohen and others to carry real time voice over Arpanet.
• 1974: The Institute of Electrical and Electronic Engineers (IEEE) published a paper titled "A Protocol for Packet Network Interconnection".
• 1974: Network Voice Protocol (NVP) first tested over Arpanet in August 1974, carrying 16k CVSD encoded voice - first implementation of Voice over IP
• 1977: Danny Cohen, Vint Cert, Jon Postel agree to separate IP from TCP, and create UDP for carrying real time traffic
• 1981: IPv4 is described in RFC 791.
• 1985: The National Science Foundation commissions the creation of NSFNET.
• 1986: Proposals from various standards organizations for Voice over ATM, in addition to commercial packet voice products from companies such as StrataCom
• 1992: Voice over Frame Relay standards development within Frame Relay Forum
• 1994: First Voice Over IP application (Freeware for Linux) ^[61]
• 1995: Vocal Tec releases the first commercial Internet phone software.^[62][63]
• Beginning in 1995, Intel, Microsoft and Radvision initiated standardization activities for VoIP communications system.

• 1996:
• ITU-T begins development of standards for the transmission and signaling of voice communications over Internet Protocol networks with the H.323 standard.
• US telecommunication companies petition the US Congress to ban Internet phone technology.
• 1997: Level 3 began development of its first softswitch, a term they coined in 1998.
• 1999:
• The Session Initiation Protocol (SIP) specification RFC 2543 is released.
• Mark Spencer of Digium develops the first open source private branch exchange (PBX) software (Asterisk).
• 2004: Commercial VoIP service providers proliferate.

CONCLUSION

                                  The speed of development and the widespread impacts of VoIP will be comparable to that of the Internet. VoIP is truly a disruptive technology that will pose many challenges to BT, its staff and its unions. The year 2003 saw VoIP move from being a fringe interest of high tech enthusiasts to a concept central to the planning of all major telecommunications operators. We shall be hearing a great deal about VoIP in 2004 in the technical media, in discussions with BT, and in discussions with members.

                       However, in some ways, VoIP is the froth on the wave and the wave itself is the 21CN/NGN. VoIP is the most predictable growth feature of the new network, but there will be many others. Here, in the UK, 2004 also sees a strategic review of telecommunications by the new super regulator Ofcom - the most fundamental examination of the regulatory structure since the duopoly review in the early 1980s. Consequently 2004 could well prove to be a watershed year for all concerned with the British telecommunications industry.

REFERENCES

1.      "Voice over Internet Protocol. Definition and Overview". International Engineering Consortium. 2007. http://www.teliqo.com/voip/. Retrieved 2009-04-27. 

2.     "IP Telephony Vs VoIP". http://www.networkstraining.com. Retrieved 27 April 2011. 

3.      "XMPP Federation". Google Talk about. 2006. http://googletalk.blogspot.com/2006/01/xmpp-federation.html. Retrieved 2012-05-11. 

4.      Booth, C (2010). "Chapter 2: IP Phones, Software VoIP, and Integrated and Mobile VoIP". Library Technology Reports 46 (5): 11–19. 

5.     "Carriers look to IP for backhaul". Telecommunications Online. January 21, 2009. http://www.commsdesign.com/showArticle.jhtml; ionid=YBQXDJILLQX0IQSNDLPSKH0CJUNN2JVN?articleID=159907138. Retrieved 2009-01-21. 

6.      "Mobile's IP challenge". Total Telecom. December 8, 2005. http://www.totaltele.com/View.aspx?ID=77588&t=4. Retrieved 2009-01-21. 

7.     Michael Dosch and Steve Church. "VoIP In The Broadcast Studio". Axia Audio. http://www.axiaaudio.com/tech/voip/default.htm. Retrieved 2011-06-21.