answer:If it is a consistent bad habit, tell her nicely that from now on when she vanishes without an explanation, you are going to hang up. Or, ask her what’s a good length for the call where she can concentrate and focus only on it? Then stick to the 5 minutes, 10 minutes, 40 minutes or 30 seconds that you both have agreed on. That way, you can hang up without being rude. Forewarned is forearmed. If she is super busy as you describe, perhaps she would appreciate shorter calls.