So no VoLTE then…
It could be the network behaving poorly (in which case it should likely happen after any call finishes, answered or not). And this unless the interruption is like a second or so - then it is intended behavior even.
Prerequisite: your phone is told by the network to change technology (to 3G or 2G) to get the call.
When that is done, it is again told to switch back to 4G. Both these are done with a more crude mechanism than connected-mode handovers, called Release With Redirect.
It differs in at least two important aspects:
The receiving end is not prepared, so you have to do setup from scratch. So even in a good case this takes a little while.
It is also not preceded by your phone having measured and reported that the target frequency is good. That is instead likely manually configured or derived by some similarly blunt logic. So if the coverage areas does not in fact overlap fully, or the config is plain wrong, you can be sent off to something that it can’t hear. Then it will waste some time trying that, and do a full search from nothing after a timeout.
Should be same as when you hand up a call.
I don’t understand what you want to get from the question(s) here. It depends!
Yes, presumably it is the closest that has the relevant technology, and presumably that’s also where you are going, but to other equipment on it.
If you meant to make a distinction with the to and from in the questions, that’s not a thing.
It’s always bidirectional but at different levels of connectedness, like currently doing something vs monitoring in case someone calls.
It not only gets released, but redirected, i.e. receives information about where to look for 4G.
In the absolute majority of cases this is actually helpful so it takes just a second or two.
But should it need to do a full scan because that didn’t work out, that takes even longer.
I feel like i’m repeating myself, and not necessarily making it any clearer. Not sure if you wanted critique on your oversimplifications or just a “close enough”. Ask more pointed questions if something is still unclear.
My phone (10 ii and latest Sailfish) loses complete connectivity to the provider (data and call) for at least 20 seconds after each call or call attempt. Is this relly regular beaviour?
I’ll alsways have to wait before I can make another call or data connectivity returns,