-Can you take a message for me?
如果不想让第三人知道,你可以说:
Can you tell him to call back?
call at+地点=visit someplace
call on sb
I will call on you.=I will call at your home.
call out=shout 大声喊
call in sb 招集和邀请
For the project,the government called in a lot of experts.