Extremely fast and lean, yet fully functional, SIP (RFC3261) and RTP (RFC3550) implementation tailored for high-performance SIP processing applications as well as small and embedded devices.
The microsippy project started with an idea to implement a lightweight framework to bring SIP UAS/UAC functionality onto high-end MCU-class devices. The ESP8266 was used as a reference platform.
Resulting SIP implementation not only achieved its original goal, but when run on "conventional" CPUs has also demonstrated capability to outperform state-of-the-art SIP engines of 2020, such as OpenSIPS and Kamailio by the factor of 5-10x.
IoT in the Age of SIP Presentation given at the OpenSIPS Developers Summit 2018 with some rationale.