tSIP: A Lightweight SIP-Based Messaging Protocol for Resource-Constrained Embedded Devices

Phone of Things (PoT) is a term recently coined in the Internet of Things (IoT) field. PoT extends the available connectivity options of IoT systems to include the ubiquitous phone network’s assets and infrastructure, leveraging them as a part of the IoT architecture. In this context, this paper proposes a constrained version of the Session Initiation Protocol (SIP), the dominant protocol used in VoIP communications. The proposed protocol, called tSIP, is a small-footprint messaging format that provides decentralized peer-to-peer communication between tSIP-enabled IoT devices. tSIP messages can also be mapped to the original SIP messages with the help of a proxy. tSIP promotes PoT and provides a standardized lightweight communication protocol between low-resource embedded IoT devices and the existing Unified Communications (UC) solution within the premises, allowing IoT devices to function as typical SIP endpoints in the VoIP ecosystem and facilitating their control and monitoring. The paper reviews the proposed tSIP messaging protocol regarding its architecture, encoding, and performance evaluation on embedded devices. The paper also gives use case scenarios for the proposed tSIP and discusses where its development will go in the future.