How to exit a phone call -- that is 'waiting'

I call a business, which is busy. They put me on hold. And hold. I want to kill/close the call. The phone display is the keypad, & at the bottom is the green button for making the call. It will not _close_ the call. It's not red. Where do I go to close/end the call? Just closing the phone app doesn't end it.

I'm working with my iPhone 12 & iOS 17.1.1