I have a Huawei Mate 10 phone that is NOT RINGING when an inbound call was made to me on an UNKNOWN number (in this case it was from Mona Vale Covid19 Testing Clinic in Sydney who were trying to notify me to proceed to the testing clinic yesterday 23.4.2020).
My phone was NOT on diversion & I was receiving calls from other numbers including the clinic's standard number 99986296 that is the initial point of contact prior to formal registration.)
This has NOT HAPPENED to me before. The only changes I've recently made to my phone was to install WhatsApp to call friends in the UK. I have uninstalled the app just in case it is interfering with my standard default phone app that I use normally to make & receive phone calls within Australia and NZ.
Not sure why that's happened, wilana. Curious to know if it's all unknown numbers or just this one example. You did specify you have no diversions in place but you can call ##21# just in case.