interjection
Standard telephone greeting; also used when testing a connection or when you think the other person may not hear you.
もしもし、田中さんですか。
Hello, is this Mr. Tanaka?
interjection
Used to get someone's attention in person, similar to calling out 'excuse me' or 'hey'.
もしもし、落としましたよ。
Excuse me, you dropped this.