Problem is when having a conference call. You have a group of people physically located in one room, joining the call from one laptop. There are other people who are physically located elsewhere joining the call as well. Problem is when the people going the call remotely (not in the conference room) sometimes can't hear what the people in the room are saying. This is because the person speaking is far from the microphone.
That problem itself cannot be solved, but the fundamental problem is that the person speaking isn't aware that their voice isn't being captured clearly via the microphone.
If the speaker could be aware of their voice is clearly captured or not when they are speaking, the speaker can take action like speaking louder, our moving closer to the microphone.
But currently the speaker just assumes their voice is being heard in the other side of the call.
So the solution is around acknowledging the speaker whether their voice is clearly being heard on the other side or not.

I assume the request for billing address is to communicate paper mails where digital communication is not possible due to either geographic or physical constraints.

The service address would be know the most used location/geographically fenced location for offering a service as those services cannot be offered reliably beyond the confines of a fenced location like emergency services or signal quality services.

Third party hardware authenticators with gps or non gps geolocation/timing could enforce such a logic to support the service.

Take the case of a homeless traveller with a PO Box and without a place to call home will not be able to avail the use free/open services like Skype.