SIMless Intranet Calling System

Abstract

Reliable voice communication is vital throughout the institutions and organizations, but it is prone to the failures of internet connectivity and cellular network in constrained or isolated settings. Our physical system is a SIM-less intranet calling platform that is going to be implemented on a Raspberry Pi based on the open-source Asterisk PBX platform to provide the Voice over Internet Protocol (VoIP) communication between SIP-based clients. Session Initiation Protocol (SIP) takes care of the registration of the user, call setup, and signalling, whereas Real-Time Transport Protocol (RTP) takes care of a data transfer, providing stable peer-to-peer communication. Softphone applications like Zoiper are used to make the connection to the users and authentication is done with the help of Asterisk configuration files like sip.conf and extensions. conf. The viability of using embedded platforms to power safe and decentralized intranet telephony was confirmed by the result of experimental tests that confirmed good connectivity, low developing latency, and audible performance. A solution suggested can be applied to campuses, laboratories, small businesses, and emergency operation where the constant use of the internal communication network is needed and does not rely on the public network. This work will help to develop autonomous VoIP communication structures which make them more robust, private, and affordable by combining low-cost hardware and open-source software.