The digital open underwater communications standard, STANAG 4748 ed 3, also known as JANUS, is a simple, robust, fixed rate, multi-access communications protocol with limited in-built security. In this paper, the authors propose a route for the evolution of JANUS through Phorcys, a secure by design acoustic communications protocol suite, that may serve as a step in the evolution of JANUS. This paper acts as the introduction of the Phorcys protocol suite, as well as the concept of the ‘House of JANUS’ as a methodology for the evolution of JANUS to provide security, flexibility and efficiency for future interoperable underwater communications.