on the phone
prep. phr..prep. phr.. Means you are busy talking to someone using a telephone.
prep. phr.. A prepositional phrase indicating that a person is currently engaged in a telephone conversation.
Sorry, my dad is on the phone right now.
She was on the phone with her sister when the doorbell rang.
The diplomat remained on the phone for hours, carefully negotiating the sensitive details of the international agreement.
This phrase usually follows a form of the verb 'to be' to describe someone's state.
Contrast 'be on the phone' (the state of being busy) with 'talk to someone' (the action); this pattern extends to other devices like 'on the computer' or 'on the internet'.
He is in the phone.He is on the phone.The correct preposition for being engaged with electronic devices like phones or computers is 'on', not 'in'.