I used to struggle with sellers yapping my ear off about their house and the closets and the new garage door opener and the color of the dining room... It's true that the only reason they ramble is because you let them!
Ask questions from the start and know what points you need to hit on for the call (hint: every call is really the same!), if they start rambling too much wait until you can get in an "oh wow, that sounds nice! By the way..." and steer the conversation back on track.