Hi. Thanks for responding!
It's for all calls--speaker phone, phone-to-ear, and using a corded earbud set. I have also tried taking it out of the case, but it still happens. It also happens to my mom, and it has happened when I'm talking to other people as well. My mom and I have the same case, as does my husband, who has not experienced this problem.
It APPEARS that noises from my tasks are interfering with/overriding my audio, which makes it sound like it's cutting out because it continues as long as I am engaging in any activity that produces noise.
I checked my settings, and "Phone Noise Cancellation" is toggled green.
I have an Invisible Shield on my phone, and it's the same glass shield brand that I have used on my previous phones.
Regarding my phone calls, I'm assuming they are cellular, but I have to admit that I haven't looked at the phone to check for that.
I would appreciate any help you can provide. We bought three new phones at one time--one for me, one for my mom, and one for my husband. He has not noted this issue with his, but all of them are iPhone 12s.