Use your own ideas. Here are some examples.
Liliana: Hi, it's me. Listen, I have a problem. Do you have some time to talk?
You: Not really. I'm on my way to English class. Can I call you back?
Liliana: OK.
You: Talk to you later.
Hans: Hi, it's Hans. Are you busy right now? I need to ask you a question.
You: I'm late for English class. I'll call you later.
Hans: No problem.
You: Catch you later.
Doug: Hey! Guess what? I have some exciting news for you!
You: I have English class so I can't talk right now. I'm going to have to run.
Doug: Fine. Call me when you get home later.
You: OK. Got to go.
Louisa: Hi! It's Louisa. I didn't understand the homework. Did you?
You: Hey, Louisa. Listen, I’m in a hurry to get to English class. I’ve really got to go.
Louisa: All right. Well, maybe we can meet in the library tomorrow.
You: Sure. I better go.