But i suspect the answer is yes, calls will come through.

What i want to know, if any android gurus shoe up, is how to roll-back to previous android version! I highly doubt its possible, but my phone just updated from 8 to 9, and my cheap-ass phone decided to not include any useful widgets! Will have to get 3rd party app just to put a clock on my home screen!

Itd be so nice if they disclosed ALL of the things that will change in an update.

If you have a phone that will allow you to unlock the bootloader. When you do your entire phone-all apps data etc will be erased and then flash the older version of android you want. Its about a ten minute job once you have everything backed up that can take you hours of reading to learn the process. If you make a mistake and something goes wrong you can brick your device. If you install a custom ROM your warranty will be voided as well. A lot of the stock widgets that ran on 8 had to be either scrapped or redesigned to work with pie. Some made it, some didn't and some that did make it still do not update quite correctly so manufacturers scrapped them in favor to people complaining their phones were crashing and wouldn't work. Digi makes a clock widget that I use sometimes that is very beautiful to look at its in the play store.

That you wipe your system cache partition while you are in recovery mode, reboot and see if that helps its not used quite like the older android versions did but it will help clear out some of the unneccessary things. You can make and receive phone calls in safe mode so if you do place it in safe mode and the problem goes away its more than likely an app. On 8.1 I heard of this happening for pixel 3 users with AT&T when the wifi signal drops out as well as the update turning the phone call notification to none instead of a sound so maybe check your ringtones as well.