Nah, that's a rookie mistake. You don't want to be the guy caught doing that when a real call comes in.
I bought a "dumb" Symbian phone and it has "fake call" functionality. It even allows you to configure which button to press and the timeout to wait for the event. If you answer it, you just hear nothing but it won't hang up on you. It's well worth the steep price of $5.
So what if a real call comes in? Just fake it, and be like hold on, I have another call coming in, "hang up" the fake call, and answer the real one.
Because phones don't "ring" when on a call - you get a beep in the phone speaker. At least with every landline and mobile phone I've ever seen in the past few decades.
I guess there is a subset of people who may still be fooled.
Or, learn ventriloquism so that you can mimic the sound of a phone vibrating on a table. Pick up the phone before anyone notices it's not moving around.