I would like to propose the Matrix standard for instant messaging (text, voice, video) and webRTC signaling: https://matrix.org/
Matrix has clients for most platforms and bridges to other protocols.
The Matrix devs are available on: https://vector.im/
Great feedback Oliver! This may be really cool for the intercom skill between units in the house (to begin with). What do you think @seanfitz?
handsfree VOIP in general will be a killer app (and a source of income?) on Mycroft: would be very useful for the healthcare sector, home assistance services, home delivery services, etc
handsfree VOIP should be better (and much cheaper in most countries) than a classic voice call with a (mobile) phone;
and webRTC has also a datachannel, which is very versatile
Something like this would have great potential to replace or extend many existing devices, e.g.: baby monitors, smart doorbells, intercoms, VOIP (audio) telephones, security devices, etc
"Amazon is taking a big step forward in its quest to turn Alexa into the operating system for the home. Starting today, the Seattle tech giant is rolling out an intercom feature for the Echo and Echo Dot smart speakers, as well as the new Echo Show, slated for release this week.
The intercom feature lets users access the speaker on one Echo device from another Echo device or the Alexa smartphone app. It builds on the Alexa voice calling and messaging technology rolled out last month."
edit: the link (mentioned in the OP) to the Matrix devs has changed: