01. to be on the phone: to be using the phone or having a conversation on the phone
She cannot talk right now because she is on the phone.
I couldn't talk to him because I was on the phone with an important client when he came.
2. an old friend: a person who has been one's friend for a long time
I met my old friend from high school last week.
We are old friends.
3. to catch up with someone: to talk to a person that one has not seen or talked to in a long time and find out about the person's life
I caught up with my old friend last night. We hadn't seen each other in over 20 years, so we had a lot to talk about.
I will meet Sally tomorrow. We haven't seen each other in a long time, so I want to catch up with her
