i phone not ringing

Hello upset1000 and welcome to Apple Support Communities.

I see you are having an issue with an iPhone not ringing.

Detect and block spam phone calls - Apple Support

Check out that article and pay special attention to the section about the new Silence Unknown Callers feature. If this is enabled and the person calling is not in your contacts, then the call will—by design—go directly to voicemail.

Cheers.

Try turning that feature off and then testing to see if the iPhone rings consistently. Attention Aware will vastly lower the volume of any notifications if you are looking at the device and may be in play here.

However, as you report that there is also an issue with not being able to be heard on phone calls, this may point to a deeper issue.

If you're already running the most up-to-date version of iOS (13.4.1 as of the time of this post), you may need to consider reinstalling iOS on your device. While this shouldn’t affect any data stored on the iPhone, it would be a good idea to make sure you’ve got a backup in place:

How to back up your iPhone, iPad, and iPod touch - Apple Support

Once you’ve successfully backed up your device, follow these steps to reinstall iOS, making sure to choose “Update” when prompted:

If you can't update or restore your iPhone, iPad, or iPod touch - Apple Support

Cheers.