Sometimes when Isabelle decides that she wants to hang out with Grandma, she goes to the door of her apartment (which leads to my basement) and simply knocks.
Amber will usually send me a text at this point saying something like "Are you home? Isabelle's knocking". Because there is no way I would hear her quiet little knocking as I am usually upstairs.
The other day, I wasn't home so Isabelle knocked and then simply sat down to wait.
She waited patiently and would not give up.
Zonked out while patiently waiting for Grandma.