We first started talking publicly about Rayo at AdhearsionConf 2011, at the same time as we were talking about building the then-new Adhearsion 2.0. Rayo was announced as a 3PCC (third-party call control) API based on XMPP that not only was to be an open standard, but have open-source implementations from top to bottom. We've been working hard ever since to make that a reality, and we're getting there at an increasing pace.
On 6th May 2013, XEP-0327: Rayo was published by the XMPP Software Foundation as an experimental standard. This is an important milestone, as it places the project in the hands of a respected standards body with a rigorous review process. The path from here is through that review process, where there will be some changes to the specification and then eventually to Draft status (which in standards body speak means "done"; how non-committal of them).
At the same time, we've been addressing the other half of "open standard"; Punchblock is an open-source (MIT) Rayo client library, and rayo-server is an open-source server implementation built on Voxeo PRISM + Moho. Additionally, Chris Rienzo from Grasshopper has been working on a server implementation as a FreeSWITCH module. This is maturing nicely and should be available within the next couple of months in newer FreeSWITCH releases.
The future is looking bright for the Rayo protocol, we're exited that we have reached this important milestone, and look forward to pushing it through the rest of the way.Ben Langfeld 06 June 2013 Rio de Janeiro, Brasil