VoIP over wireless networks

Voice over IP and wireless are revolutionary technologies by all means of modern time which change the attributes of communications dramatically. VoIP is simply the transmission of voice traffic over IP-based networks. VoIP has become popular largely because of the cost advantages to consumers over traditional telephone networks whereas Wireless communications is a rapidly growing segment of the communication industry, with the potential to provide high-speed high-quality information exchange between portable devices located anywhere in the world. Since both technologies have shown their existence in today?s communication industry individually, merger of these technologies was necessary and hence both technologies are being deployed.In this thesis, the VoIP technology is examined by regarding its general structure, fundamental components and operation logic. In addition to the detailed explanation of VoIP procedure, the simple VoIP prototype in wireless networks was implemented. Codecs, signaling protocols, real time protocols and media gateway protocols are the main principles of the VoIP technology. These principles and the components such as end systems, signaling servers and media gateways are used to define and implement VoIP process.A VoIP Phone system requires the use of VoIP phones. VoIP phones come in several types. In this prototype, software based phones (Soft Phones) are preferred. Sipdroid application which runs in Android mobile phone and Peers application which runs in PC are used as SIP clients. These applications use G711 codec technology, SIP signaling and RTP real time protocols. The SIP accounts which are necessary to run these applications are obtained from a free signaling server called as Sip2Sip. This signaling server is responsible from setup of the SIP session establishment and control of the routing of signaling messages.In order to provide wireless network access to each SIP client, Cisco access points are used in this prototype.