[Ring] Feature - Intercom

[Óvári]

Hello!

1. Ring can now successfully make an intercom call, i.e. a call 
originating from and destination being the same username.

This successfully works between 2 Linux computers.

2. The intercom feature is a useful and unique feature not found in 
other VoIP solutions and should be displayed at:

a) Where appropriate on the official Ring website, i.e. https://ring.cx/

b) https://en.wikipedia.org/wiki/Ring_(software)#Features

2. Unfortunately, it does not currently work between an Android 
smartphone and Linux computer. Hopefully this feature will work soon.

https://tuleap.ring.cx/plugins/tracker/?aid=1649#followup_10113

3. Keep up the great development work!

Thank you

Óvári