PoT: bridging IoT with phone technology

Abstract

The ”Phone of Things” (PoT) introduces an innovative integration of IoT systems with the widely available telephone network infrastructure. It repurposes underused home landlines and existing communication servers, weaving them into the IoT fabric. By transforming IoT devices into SIP endpoints within the VoIP ecosystem, users can monitor and interact with these devices through regular phone calls, voice commands, or text messages. PoT presents a seamless user experience by capitalizing on ubiquitous phone network infrastructure while promoting context-aware telephony solutions. Using open-source technologies, PoT ensures affordability, interoperability, scalability, and security. A tangible PoT prototype is developed using a Raspberry Pi equipped with Asterisk, a renowned open-source IP-PBX software. The Raspberry Pi acts as a gateway, facilitating communication between IoT devices and VoIP servers. Performance evaluation testing reveals that the Raspberry Pi 4 B can manage up to 182 concurrent calls, while the less performant Raspberry Pi Zero W can handle 12 simultaneous calls. These results highlight the potential of these compact, affordable boards as ideal PoT gateways for homes and small-to-medium businesses, making deployment of the framework more economical. In addition, the thesis introduces ”tSIP”, a streamlined SIP version designed for PoT. It offers a concise message format, achieving up to 22% and 46% size reduction compared to traditional SIP and CoSIP messages. This compact format ensures quicker transmission, energy efficiency, and optimized network usage. The study also presents a decentralized registration and authentication mechanism for PoT, based on blockchain technology. A prototype is crafted on a private blockchain, emphasizing privacy, speed, and cost-effectiveness. This mechanism aligns with SIP’s security standards and caters to embedded smart devices’ constraints. Lastly, to illustrate PoT’s real-world application, the ”Location Transparency Call” (LTC) system is introduced. LTC provides a context-aware telephony solution for businesses. It tracks employees via their RFID access tags, ensuring that incoming calls are redirected to the nearest phone to their current location, reducing missed business call occurrences.