I myself was moved to digital voice last September and the phone has worked exactly as it did before ever since.
I’m perhaps not the best person to answer your questions. There are more knowledgeable people on here but as no one else has done so, I’ll try to give you some answers. I’m sure I’ll be corrected if I’m wrong.
In reverse order:
The recent outage was more an industrial thing and hyped up by the media. Myself, (and I’m sure the vast majority of ordinary users), did not even notice. Certainly, there was no disruption to digital voice that I was aware of. The biggest problem is that it will not work during a power cut. Whether that’s a problem depends on where you live and how often you get power cuts, of course. It is possible to get a battery backup for it.
Can they opt out is a little more difficult to answer. I believe BT will not proactively move anyone against their objections but the reality is that the old phone system is obsolete, falling apart and becoming difficult to get spares for, as no one makes them anymore. Eventually, everyone will have to move, if you still want some sort of phone service.
Moving to another provider is a waste of time. This is not just a BT issue, although they’ve taken most of the flak for it. The same situation applies to all of them. Sooner or later, they will all go the same way. At least BT have provided some sort of alternative solution. A lot of providers are not providing a phone service.
As I understand it, essentially, they won’t have “the internet”. What they will have is a box that plugs into a power point. The phone then plugs into that box and the box plugs into the phone socket. It should work on the defaults and be no more difficult to setup than changing a light bulb.
