This is an important issue to resolve. There are many clues st the start of the thread. Then from our Admin in Post #12
I have shared this thread with the developers. Wanted the names of the carriers and location where this issue is being observed.
Those who are facing this issue please provide country you are located in and the service provider name.
The way that carriers get correct connection to an AOSP device changed about January 2026. Please read those early posts.
A solution to what sounds a similar issue was resolved like this Incoming phone calls not received - #18 by Yogi.