be on the telephone

Từ điển Oxford Advanced Learner 8th

be on the ˈtelephone idiom
1. to be using the telephone
•He's on the telephone at the moment.
•You're wanted (= sb wants to speak to you) on the telephone.
2. (BrE)to have a telephone in your home or place of work
•We're not on the telephone at the cottage.
Main entry: ↑telephone_idiom