You're Expecting An Important Call From Mr. Suarez, A Potential Customer. While Waiting For This Call?

You're Expecting An Important Call From Mr. Suarez, A Potential Customer. While Waiting For This Call, Your Supervisor Calls From London To Update You On The Progress Of A Report. If Mr. Suarez Calls While You're Talking To Your Supervisor, which specialized telephone feature will ensure that you don't miss his call?.