be on the phone
idiom.idiom. To be busy talking to someone using a telephone.
idiom. To be currently occupied with a telephone call; the phrase functions as a predicative complement to the verb 'to be'.
She is on the phone right now.
I tried to call him, but he was on the phone with a client for an hour.
Despite the urgency of the evacuation order, the manager was on the phone, seemingly oblivious to the chaos erupting around him.
Refers to the state of being engaged in a call, not just holding or looking at a phone.
Point out the prepositional difference between British English ('on the phone to someone') and American English ('on the phone with someone').
She is in the phone.She is on the phone.The correct preposition to describe being engaged in a call is 'on', not 'in'.