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IP Telephony

IP Telephony is a general term for technologies that use IP-based networks to build, provide and access telephonic communications. IP Telephony, which is part of the TCP/IP protocol suite, is a two- way transmission of voice over a packet-switched IP network. Replacing the telecommunications’ infrastructure of the traditional circuit-switched public data networks(CSPDN) and public switched telephone networks(PSTN) with the packet-switched IP communication network, IP Telephony is able to exchange voice, fax and other form of communication through the help of the internet via the Internet Service Provider(ISP) or directly from a telecommunication service provider. IP Telephony service providers include telecommunication companies, local telephone companies, cable Tv companies, Internet service providers(ISPs) and fixed service wireless operators.

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In a consumer context of using the IP telephony solution, with the availability of internet connection and a phone communication application – like Skype, that enables voice and data communication such as calling and faxing to another phone user. IP Telephony also allows communication with circuit switched and cellular communication services. Working on top of an IP network infrastructure, IP Telephony is implemented through IP phones in an enterprise environment.

Basically, IP Telephony deals with the digital side of telecommunications and internet protocols(IPs) are required for IP Telephony to work as it helps to define how data is to be understood, formatted and transmitted over a network to be displayed in web servers and browsers. Voice over Internet Protocol (VoIP) is a popular IP telephony implementation which only supports voice communication over IP. With the solution of using the internet, through IP Telephony, forms of communication can now travel as packets of data on shared lines which can be used to avoid the restrictions and limitations of the PSTN. The restrictions and limitations of PSTN include the high cost of usage and remote extension and poor scalability.


How IP Telephony works?

For it to work, IP Telephony uses two protocols – one is for signalling and one is for transport. The protocol that provides for transporting of voice packets is the User Datagram Protocol(UDP) and either Transmission Control Protocol(TCP), Session Initiation Protocol(SIP) or UDP is used for signalling. Signalling commands that are defined in signalling protocols to be able to establish and terminate calls, provide special features such as call waiting, forwarding and conference calling.

Since IP Telephony uses IP for voice transmission and communication through packet-switched network of TCP/IP protocol suite which is a set of rules to adhere to during any communication using the Internet. The rules are as of followed: Information is divided into a number of chunks called packets when it is to be transmitted. Computers that are used for communication has it own particular IP address. Packets of information, that contains the IP address of the sender and receiver computer, will be transmitted to the gateway computer when communication takes place. After reading the receiver address of each packet, the gateway computer sends the packets to their respective destination without any particular order. TCP will then ensure that packets will reach the destination computer in the correct order. IP requires no specific physical medium and is a protocol that needs no connection for communication.



Diagram 1


Diagram 1 shows the integration of the traditional SS7-based telephone system(PSTN) with the IP Telephony carriers, packet-switched IP. This system is a complex undertaking with many protocols competing for attention. The red lines represent the signalling, the blue lines represent the voice packets and the green lines represent the TDM (circuit switched). From Diagram 1, it clearly shows that with the help of IP Telephony with the protocols, different forms of communication data can easily be transmitted to another network, in the same single converged network, which is located at a long distance away. With the integration of the PSTN and the IP Telephony, the system will not be restricted to the tolls of the PSTN since there is always another alternative – packet-switching IP.

Since PSTN is a long-distance infrastructure network of noise-oriented public telephone, the ISPs use the PSTN for communication over a long distance. The 2 PSTN that IP Telephony use is dial inward dialling and access number. When using the access number network of PSTN, an extension number is required but no extension number is required for direct inward dialling.

Traditional telephone communication and voice communication over the Internet (IP Telephony) work differently. For traditional telephone communication, the purpose is to talk directly to another person through telephone exchange. The connection is through a telephone line which voice is transmitted over. However, IP Telephony works in a completely different way.

IP Telephony system process starts with the telephone signal transmitting to a gateway (Shown in Diagram 1). The gateway will then check if the signal is digital. If it’s not, the process of digitalizing becomes mandatory. Next, the data is then compressed and divided into packets to be transmitted to the endpoint using TCP/IP protocol. For the recipient to be able to listen to the voice (original signal) of the other person, the IP packets will be decoded to convert digital signal back to original signal. This whole process of signal transmission occurs almost simultaneously so that users would not experience any delays or interruption of sound. Speed and reliability of connecting users to internet determine the quality of the communication.

An IP Telephony system can be an IP-PBX system which has VoIP- means of transmitting voice for the implementation of the IP Telephony system and its standards, SIP.

Diagram 2


IP Telephony system consists of SIP phones, an IP PBX server which functions like a proxy server and a VoIP Gateway to connect existing PSTN lines. IP phones, which are SIP clients, register with the IP PBX server and request connection when user wishes to make a call. This is all possible due to IP PBX having all corresponding SIP address of clients which enables it to connect clients either through a gateway or service provider(VoIP)


Finally, there are various methods of communication in IP Telephony. These include Computer-to-Computer and Computer-Phone that requires an application like Skype, as well as Phone-to-Phone which is the ordinary cellular operators and Surf & Call which is often used by commercial companies to make calls directly from the site.

What is IP telephony and how does it work?


Potential Benefits & Negative Implication of IP Telephony

Diagram 3


There are many benefits to using of IP Telephony. Though the use of IP Telephony, organizations are able to build an independent infrastructure that supports their company’s data and voice communication needs. Ever since the implementation of IP Telephony, which uses Voice over Internet Protocol(VoIP) technology for telephone calls, businesses are able to overcome the limits of the traditional phone systems through the integration of both computer and telephone networks. The benefits of IP Telephony are as of followed:

Saving of costs on phone calls significantly and enhanced performance- When the IP Telephony system is implemented in an organisation, Analog phone lines are no longer needed since IP Telephony system uses the Internet to transmit both voice and data. This means that the organisation can avoid the imposed fee of the telephone companies which would lower operational costs over time. Additionally, IP Telephony system being able to support a huge number of applications, it has enhanced the productivity of organizations as employees can carry out their tasks more efficiently and effectively. Such application includes Skype, TeamViewer, IP SoftPhone etc… IP SoftPhone, for example, is a software-based application which allows users to incorporate their phone functionally into their PCs. Being able to use skype when there’s a need for face-to-face business conferences, it helps organizations save their expenses of business travel.

Improvements to the connectivity and mobility- Organizations can communicate almost anywhere around the world, as long as there is internet connectivity, since IP Telephony systems transmit data over the internet. IP Telephony provides innovative solution for communication such as uniting mobile workers into a single converged network through the unification of many different locations within a business firm. This also implies that with the multi-site connectivity through data network that IP Telephony offers, organizations do not need pay for long-distance charges and do not need to change their numbers, which using the traditional Analog phone lines do. With the implementation of the IP Telephony, WiFi IP phone is also introduced. This means WiFi IP phone being wireless can completely eliminate reliance on wires which allow users to have more mobility around the workspaces and be able to receive calls in remote locations.

Multitude of innovative feature that comes with the IP Telephony- IP Telephony systems have push the boundaries of the way businesses communicate as it could do much more than the old telephony systems. Rather than just being able to make normal phone calls, IP phones can now do much more. Some of the features of modern-day IP Telephony systems are caller ID, call waiting, voice mail to email transcription, unified messaging, teleconferencing capability and the list goes on…

Easy configuration and installation- Compared to the traditional phone system, IP Telephony systems are much easier to configure and install. Technologies used by phone companies, such as the proprietary software and graphical user interfaces, can be very complex and confusing for people. Whereas for IP Telephony system, people who are more familiar with networking can easily understand how to configure and install it.

High degree of survivability and scalability and improved business resiliency – IP Telephony system are never restricted by a maximum number of physical phone connection since organization can simply just connect a new IP phone to the network, via the router, when it is needed. Structured in a way to detect and eliminate points of failure, IP Telephony solutions can be dissipated to safe guard against local hinderance to service. It also can automatically redirect voice, data and video traffic around failures. The scalability and flexibility that IP Telephony systems provide allows companies to grow and expand or scale back easily.

Faster customer respond time- Customer satisfaction is very crucial to the success of any businesses. Fast and good communication is vital for maintaining customer reliability. IP telephony provides effective communication with their customers which will definitely benefit business organizations.

IP Telephony is almost implemented in every organisation today. It is so essential that it becomes mandatory for all organisation due to its endless list of benefits. However, nothing is impeccable in this world. Some of the flaws of IP Telephony include:

With the absence of internet access, IP Telephony has limited or no use at all. IP Telephony systems, unless there is an integrated compatibility of a PBX system in place, does not have any accommodation for calls beyond the organization’s LAN. Unstable or delays in broadband (internet) connection will also result in packet-loss and latency. This means that communication might be distorted and garbled due to transmission error.

Network easily congested- Especially for residential internet connectivity, network would easily lead to congestion which will result in poor voice quality or slow data transmission. Sometimes when the network is congested, a complete call-drop may happen. This is dangerous when it comes to situation of an emergency. When there is a delay in the connectivity, IP Telephony system will fail to function effectively. An example of such situation is when IP telephony being exposed to satellite internet integration.

The challenge of emergency calls- Since IP Telephony uses a special IP-address phone number for each IP phone (not the regular public-service phone numbers), it becomes extremely difficult to surpass an emergency. It would be hard for the 911 emergency dispatch operators to identify the exact location of the given IP address.


How company can make use of IP Telephony

CD-Forensic (security company) can make use of IP Telephony systems to avoid the tolls of the traditional phone system, the limitation of using just PSTN, by integrating the PSTN with the IP Telephony carriers, packet-switched IP. This would allow communication between the LANs of CD-Forensic over to a far distance – since the LANs are located rather far away from one another.

However, before implementing the IP Telephony system, and to be able to benefit and take full advantages of its use, certain degree of planning is needed to know the objective of the implementation. For CD-Forensic, a security company, which provides security services and expertise to their client. Being able to reach out to the other LANs to pass information around efficiently and reliability is important.


Since IP Telephony allows networks to be unified and converged, where calls travel as data over the internet like emails, having a single converged network with multiple purposes can help CD-Forensic relieve them encumber on admin as well as reduce cost of admin as they no longer need to maintain multiple networks. If CD-Forensic have its own phone system already(tradition), it can be upgraded to IP Telephony system to further enhance effectiveness of communication through a VoIP Gateway to connect the existing PSTN lines. Unified messaging of IP Telephony also helps CD-Forensics to save time on information management

After implementing the IP Telephony system, as long as there’s internet connectivity, CD-forensic can also save on the cost of long-distance charges (toll bypass) and telecommunication charges when communicating among LANs since IP Telephony system transmit data over the internet. If CD-Forensic were to use the traditional PSTN phone system to communicate internationally, the cost of the phone bills would be extremely expensive compared to the IP Telephony system.

To think ahead for CD-forensic, if they would to expand their company in the future or would like to add additional equipment, IP Telephony helps to keep the cost of Moves, Adds and Changes down since it is very flexible. A college in Florida, for example, used to be charged by their previous PBX provider $70 per move, add or change which usually the college would have lots of maintenance and renovation – their monthly relocation cost was extremely high. However, after implementing the IP Telephony system, that college had saved $16,000 a month since the cost of moves, adds and changes become virtually free as whenever they change locations, plugging their phones into an Ethernet jack is all that they need to do to relocate. This shows that it proven true that the maintenance cost of the telephone system would greatly reduce with the implementation of the IP Telephony system

Not only just reducing the cost of maintenance, IP Telephony’s flexibility also allows faster and easier moves, adds and changes (e.g. setting up of IP phones). With IP Telephony implemented, there would not be a need for technician to come down to the location to support and guide employees how to set up the phone systems since the IP Telephony system is rather simple and straightforward, unlike the traditional telephony systems. For the traditional telephony systems, it may even take a few days to complete the fixing and placing process with a technician. Therefore, with IP Telephony, CD-forensics can fret not about the moving, adding and changing process.

IP Telephony system would also benefit CD-Forensics as it provides their employees with easy usage of calling features and the ability to telecommute with one another. The 4-digi dialling, that the Unified Messaging offers, allows efficient telecommunication. With IP Telephony, employees can also work at home as data can be transmitted through the internet. Skype and TeamViewer, for example, allows video conferencing anywhere which have internet connectivity and at any time. This will eventually lead to the improvement of productivity in CD-Forensics as convenience and comfort of their employees would improve their satisfaction.


Potential challenges

Since IP Telephony relies on the Internet, call quality can be erratic as the Internet provides no constant guarantee of stable connection and quality of service(QoS). This means that users of the IP Telephony may experience call-drop at times if there is a latency in the Internet connection. Only if the organization has control over their own IP network, quality would then be excellent.

It is easier than said than done. Installing a IP PBX together with a traditional PBX may be very challenging and most of the time- not possible. It may be very costly to implement and integrate both together or its not possible due to technical reasons. There might be a need for an upgrade their existing network infrastructure to support IP telephony. Failure when integrating the IP Telephony alongside with other digital equipment may also happen. This means that the technology would become redundant when incompatible digital equipment is introduced to the telephone system. Such digital equipment that may not work with IP Telephony system is home security systems and digital video recorders. It is also said that IP Telephony requires additional bandwidth capacity.

IP Telephony systems, like any other internet integrated networks, may also be susceptible to attacks like the Denial of Service attacks (DoS attack) from viruses and hacking. When processor drain due to the attacks, it may lead to frequent loss of quality of communication and maybe even lead to system-crash – since IP Telephony system relies on the power of integrated PCs. However, since CD-Forensic is a security company, security of the company should already have a high level of assured security so the problem of chances of receiving a attack is very minimal. But, that does not mean it is not possible.



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