Wouldn't it be great to use your Amazon Echo to make calls?
When you break it down, the Amazon Echo has 3 basic components, a microphone, speaker, and Internet connection. To me, that's all you need to use the Echo as a communication device.
The simplest form of communication would be from Echo to Echo, right in the same house, as an intercom system, so you can reach any room in the house by simply asking Alexa to connect you to another room. Taken one step further, you could use it to turn on the microphone in a baby's bedroom, so you can use it as a baby monitor.
Naturally this leads to yet an even bigger step. If you could connect from room to room, why not connect you to another Echo, or even another phone anywhere around the world?