You should answer the phone when your parents call.
Sally is really busy at home doing a bunch of housework and her phone rings with the caller ID showing it is her parents.
Sally wants to finish her housework.
Sally knows that her parents could be calling about something important, so she picks up the phone while continuing her house work with her free hand.
Sally decides to ignore the call from her parents as to not interrupt the housework she is doing.
Sally's parents inform her about something that is extremely important and Sally is glad she answered.
Sally misses important, time sensitive, family news that her parents were trying to contact her about.