1.1 Introduction
VoIP is an acronym for Voice over Internet Protocol which is a technology that allows mobile users to make voice calls using a broadband Internet connection instead of a regular (or analog) phone line. Voice over internet protocol (Voice Over/P, Vo/P) is a family of technologies, methodologies, communication protocols, and transmission techniques for the delivery of voice communications multimedia sessions over internet protocol (IP) networks, such as the internet. Content telephone refers to communication services-voice, fax SMS and/or voice-messaging application hat 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 analogy voice signal, encoding packitization, and transmission as internet protocol (IP) packet over a packet switched network on the receiving side, similar steps usually in the reverse order such as reception of the IP packets, decoding of the packets and digital-to-analog conversion reproduce the original voice stream.
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Limitations of the Study and Definition of technical terms.
1.2 Background of Study
VoIP systems employ session control protocols to control the setup and tear − down of calls as well as audio codes which encode speech allowing transmission over an IP network as digital audio via an audio stream. The codecs used is varied between different implementations of VoIP (and often a range of codecs are used). Some implementation rely on narrowband and compressed speech, which others support high fidelity stereo codecs. Even through IP Telephony and VOIP are terms that are used interchangeable, they are actually different IP telephone has to do with digital telephony system that use IP protocol for voice communication while VoIP is actually a subset of IP Telephony. VoIP is a technology used by IP Telephony as a means of transporting phone calls.
VoIP is available on many smartphones and internet devices so event the users of portable devices that are not phones can still make calls or send SMS text messages over 3G or Wi-Fi. VOWLAN (Voice Over Wireless LAN) is the use of a wireless broadband network according to the IEEE 802.11 standards for the purpose of vocal conversation. In essence, its VoIP over a Wi-Fi network. In most cases the Wi-Fi network and voice components supporting the voice system are privately owned.
VOWLAN can be conducted over any internet accessible device, including a laptop. PDA or the new VOWLAN units which look and function like DECT and cell phones, just like for IP-DECT, the VOWLAN’S main advantages to consumers are cheaper local and international calls, free calls to other VOWLAN units and a simplified intergrated billing of both phone and internet service providers.
Although, VOWLAN and 3G have certain feature similarities, VOWLAN is different in the sense that it uses a wireless internet network (typically 802.11) rather than a cellular. Both VOWLAN and 3G are used in different ways, although with a femtocel the two can deliver similar service to users and can be considered alternatives. Voice over Internet Protocol, sometimes known as VoIP, is the process of transmitting voice calls via data networks (Nisan et al., 2011). Packet switching is the technology that underpins data networks like the internet, local area networks (LANs), and wide area networks (WANs), which all make use of internet Protocol (IP) (Zhang et al., 2011). This does not mean that Voice over Internet Protocol (VoIP) traffic is sent over the internet; rather, it indicates that the same Internet Protocol is used (Olejniczak, 2009).
Speech over Internet Protocol, which is also known as IP Telephony, is a technology that integrates many modes of communication, such as voice, video, and data, into a single network. Because of this, it is now possible to control both data and voice traffic on the same network. These many kinds of IP packetized communication are sent across an IP-based network that is privately controlled (Costello & Lassman, 2004) As a result of the fact that Voice over Internet Protocol (VoIP) technology evolved with various favorable characteristics over the older standard Public Switched Telephone Network (PSTN), VoIP is rapidly replacing PSTN.
In contrast to PSTN, Voice over Internet Protocol (VoIP) is not limited to only making and receiving telephone conversations; rather, it incorporates all other types of communication, such as videoconferencing, voice mail, email, call waiting, call identification, faxes, and so on. Because of its many benefits, Voice over Internet Protocol (VoIP) is progressively replacing the more conventional PSTN. The use of Voice over Internet Protocol (VoIP) has helped break down barriers in international communication by offering an alternative to traditional phone conversations and facilitating easy access to low-cost calls using a computer and the internet. In contrast to the PSTN, which requires a significant investment of cash, the deployment of VoIP networks is quite affordable.
1.3 Statement of Problem
Investigation revealed that in VOIP system, there is issue of power failure and backup system are mentioned. Traditional telephones operate on internal 48 volt internal power supply. Therefore it can still continue to work even if there is power outage. So, they need to have backup power system using Uninterruptible power supply (UPS) and proper power back up assessment done regularly to ensure there is sufficient power for the VoIP system.
The use of softphones software is another challenge of VoIP implementation. These softphones are vulnerable to worms, virus, Trojan horses and spyware attack and can compromise the security of the network. Computers connected to the Internet can be attacked if a user visits a compromised website even if he/she did not open the website.
Traditional PSTN telephone can provide emergency calls because it is tied to physical location and emergency service provider can easily track caller’s location to the emergency dispatch office. But an individual using VoIP network can be from anywhere around the globe, thereby making emergency call location difficult because the caller’s location and identity can’t be traced easily. Even if the VoIP service provider can provide for emergency calls, there is lack of standard in VoIP environment.
1.4 Aim and Objectives of the Study
The aim of the study is to design and implement a Wireless Voice Over Internet Protocol System. In achieving this aim, the following specific objectives were laid out as follows to develop an application software that will:
- Authenticate calls and end points protection from insecure of network resources;
- Protect the privacy of call conversation over internet network;
- Secure caller behaviour or statistical information from authorized access;
- Protect network servers and endpoints from well known threat and attacks; and
- Ensure correct billing by the service provider and protect billing information from authorized access.
1.5 Significance of Study
The proposed system will reduce the cost of buying network equipments and wiring. IP network equipments are very cheap, interoperable and can be sourced from multiple vendors compare to traditional PSTN landline equipments. Another significant reason for deploying VoIP is because it can reduce the cost of making long distance calls. Softwares such as Skype, Windows live messenger e.t.c allow free PC to PC calls. Calls to mobile and landline are at reduced price.
Also, VoIP network enables multimedia applications, voice and data such as voice/video conferencing, white boarding, file transfer to increase productivity and creates a more flexible. This study will be of immense benefit to other researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.
1.6 Scope of Study
The scope of the research is focused on the Design and Implementation of Wireless Voice Over Internet Protocol.
1.7 Limitations of the Study
During the course of this study, many things militated against its completion, some of which are:
- Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
- Establishment Policies: Establishment policies posed a serious limitation as most staffs are not ready to release information needed for this project work. There were lots of information needed from the staffs of this institution to enhance the study which took them time to release or they did not release at all for security purposes, hence the scope was reduced.
- Research material: availability of research material is a major setback to the scope of the study.
- Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
- Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet).
1.8 Definition of Terms
VoIP: It stands for Voice over Internet Protocol which enables mobile users to compress and convert voice signal to digital signal and transmit it through Internet Protocol (IP)-enabled network
Wireless Internet Networks: The unprecedented increase in access to telephone services growth has been driven primarily by wireless technologies and the liberalization of telecommunications markets, which allowed for faster and cheaper roll out of mobile networks.
