https://www.theverge.com/2018/10/11/17964940/amazon-echo-smart-camera-doorbell-connect

Amazon is introducing some new software tools allowing developers to connect smart cameras and doorbells to Echo devices. Specifically, Amazon has released the Doorbell Event Source, Motion Sensor, and Alexa.RTCSessionController APIs (application programming interfaces) in the US, with additional regions coming soon.

What each API offers to Alexa and Echo devices is different, of course. For example, smart doorbells can now ping all Echo devices to make an announcement, alerting you to a visitor or transmitting a message. The Motion Sensor API reports on the state of endpoints, which is useful for security cameras and could let the devices detect movement in a given area. And finally, the Alexa.RTCSessionController can establish a two-way link between smart displays like the Echo Show and Echo Spot.