Without being able to get too into the telco detail, I think the lesson was that hard realtime is both much harder to achieve and not actually needed. People will happily chat over nondeterministic Zoom and Discord.
It's both psychological and slightly paradoxical. Once you let go of saying "the system MUST GUARANTEE this property", you get a much cheaper, better, more versatile and higher bandwidth system that ends up meeting the property anyway.
Seeing that the tech would never be good enough, they sold off the whole thing for cheap. Years later, they bought it back for way, way more money because they desperately needed to get into the cell phone business that was clearly headed to the moon.
I totally understand the pride they had in the reliability of their system, but it turns out that dropped calls just aren't that big of a deal when you can quickly redial and reconnect.
Those old phones had a long range. It was hard to make small ones because the old AT&T towers were much farther apart, up to 40km. Meanwhile, their competitors focused on smaller coverage areas (e.g. 2km or less for PCS) and better tech (CDMA), and it seemed to pay off.
It wasn't until phones shrank and service got cheaper, that consumer adoption took off. Businesses and early adopters will pay even if the product is inconvenient and costly to use, as long as the benefit exceeds the cost.
Well, not "happily". (Doesn't every video conference do the "hold on, can you hear me? I have wifi issues" dance every other day?) But it works on a good day.
In my club when there is a virtual club meeting however, where people don't have frequent video meetings there is always somebody with trouble ... often the same.
Zoom, on the other hand.. I have weekly Zoom meetings and never had do to the "can you hear me" thing. Or in fact with basically anything which is not Teams.
In any case.. it's not the network, it's the application/service.
What you need is more that enough bandwidth.
Think of the difference between a highway with few cars versus a highway filled to the brim with cars. In the latter case traffic slows to a crawl even for ambulances.
It seems like it was just cheaper and easier to build more bandwidth than it was to add traffic priority handling to internet connectivity.
That was a selling point, because "hey we guarantee this circuit" but it was also very expensive and labor intensive
Where just dumping your bits into the internet and letting the network figure it out outsourced a lot of that complexity to every hop along the network you didn't own. But, because they care about their networks everyone would (in theory) make sure each hop was healthy, so you didn't need to hand hold your circuit or route completely end to end
Only because they don't even know how a good system feels like
