Hello,this is xx speaking.
（如果明显不是找你的话）Are you looking for someone?
1.如果他要找的人不在：Well,look xx is not here now...but you can leave a message if you want to,then when xx is back I will tell him/her.
情况a) (如果对方愿意留下message) Ok,so what's your name?is that ok if she call this number back?(因为有的人可能用公共电话,所以要确定联系电话)
情况b) (如果你知道你的家人/朋友什么时候回来)I think she/he will be back at xx(时间).Would you like to call back then?
2.(如果你朋友在的话) Yes she/he is here.Hold on,I will let he/she to speak to you.