Ringer gets quieter after I pick up phone but still ringing

I talked to Apple a couple years ago about this, but now forgot how to change. When my phone rings, and I pick it up the sound of the ringer gets quiter, still rings just not as loud. I don't want that, and there is a way to change it so, after phone is picked up it stays loud. But don't remember how to change and can't find my conversation with apple on how to fix it.