Abstract
VoIP (Voice over Internet Protocol) refers to a communication mechanism in which voice and/or multimedia maybe transmitted over the internet in the form of digitized packets. VoIP quickly became an important part of digital communication and audio engineering discipline because of its versatility to support various features. It advanced tremendously over the last few years mainly because of the internet boom, cost benefits and the flexibility of communication that it offered over the internet. Depending on their implementations, VoIP sessions can use a wide variety of protocols to establish and terminate sessions. Based on the type of application or scenario in which VoIP is used, the speech signal can be encoded and decoded using different standard codecs before they are transmitted over the network as packets. The main aim of the project was to design a billing system and write Java code to enable VoIP communication between two computer systems using SIP protocol. This project used open source sip-communicator based code as the main framework to implement VoIP communication. At the Application layer, Session Initiation Protocol (SIP) controlled Signaling (including session initiation, session termination) and communication sessions while Real-time Transport Protocol (RTP) defined the format for voice/media data over the Internet. This project also used two test accounts created on a back end SIP server to test the VoIP implementation and transmission in real time. A local system Oracle database was designed using (Structured Query Language) SQL and it stored and retrieved all the call statistics such as caller, callee, start time, end time, total duration information, using which the total billing amount was calculated and displayed along with the caller and caller user accounts information.