Thanks for the reply!
My goal is to pause the timeline, if someone speaks in the given "scene". For that, I'm using the keyframe tag option. It works like a charm. In that moment, I show the user some text, and I want some action from the user, to resume the timeline. I want to give enough time, to read it. And for resuming the timeline, I have to identify it somehow. My process now is when I start playing the timeline, I give a tag for it, and I store that tag in a global variable. After the timeline reaches the keyframe where someone starts to speak, I pause the timeline, and in a key pressed event, I resume it with the timeline tag, what I gave it before. After the timeline completes, I clear the global variable.
My original problem was that I didn't understood what tag the resume method needs. But it works now :)