What does “de la part de” mean in French?

De la part de marks who something comes from when it is passed along by someone else: c’est de la part de ma mère is “it’s from my mother.” Part here is a share or a side, so the phrase sits close to “on behalf of.” It labels presents, messages and greetings alike — dis-lui bonjour de ma part is “say hello from me.”

The same phrase runs the French telephone: c’est de la part de qui ? is the standard “who’s calling?”, asked by whoever picks up for somebody else. It sounds odd translated word for word — “on whose behalf is it?” — but that is exactly the logic, since the caller is being announced to the person they asked for.