Yep. I do the same thing with that sort of call, especially to my work phone.
Depending on the mood I’m in, I’ll either be polite, or I’ll just string them on until they hang up.
Although I do wonder why no one wants to sell me an extended warranty for my 1959 Morris Oxford… 
Another gag I’ll pull on warrenty people, especially if I don’t have time to string them out, is to ask “which one? I’ve got 200 on the lot here.” :pause for effect: “You’ve reached a used car company.”
I do block the number post call, which at least tells Apple (if they do such things) that the call was likely spam or junk. I know that Google Voice (or what’s left of it) does something similar across the aggregate of calls they handle.
