the feature you are referring is called "Call Waiting".
The path to find it in the admin portal is:
Users > Click on a user > Call Handling > Settings (attached picture)
Afaik this setting is present on most accounts with the exception of some partners of RC? I have it on mine.
So what you are describing is that you want to have Call Waiting enabled for the attorney. This way if the attorney is on a call and the receptionist calls them, the attorney would hear a tone and will be able to choose what happens with the 2nd call (accept it, ignore it, send it to voicemail, etc.)
By default Call Waiting is on, so it should be working the way you want it to, unless you have changed this and forgot about it. If call waiting is on, but the attorney still is not getting the announcement of the 2nd call, could be "bad" notification settings on the app the attorney is using.
