Color for an inbound phone call vs color for an outbound phone call

What is a good color to use to signify an inbound phone call vs a good color for an outbound phone call?

• An outbound phone call would indicate an action that is being taken.
• An inbound phone call would signify a more passive role in responding to an external event.

This is what I have so far. I'm thinking red for outbound since its more or an active role and blue for incoming since its more of a passive role. However I know almost nothing about color theory...