Here's the completion of the phone conversations:
**Conversation 1:**
A: Hello?
B: Good morning. Could I **speak** to Luke James?
A: Who's **calling**, please?
B: **It's** Liam Matthews.
A: One moment, please. I'm **putting** you through.
C: Hello?
B: **Hello**, Mr James?
C: **Speaking.**
**Conversation 2:**
A: Good morning. Boulding Limited. Can I help you?
B: Yes. I'm trying to contact Oliver Fallow. He left a **message** on my **voicemail**.
A: I see. Well, I'm afraid Mr Fallow's **out** at the moment. Can I ask him to **call** you **back** later?
**Conversation 3:**
A: Hello.
B: Hi. **Is that** Carlos?
A: Yeah, speaking.
B: Hi Carlos, **it's** Serena.
A: Oh hello. I was expecting you to ring last night.
B: I did, but I couldn't get **through**; the line was **busy**.
A: Oh yes, I'm sorry about that. I was **on** the phone to my brother for about an hour.
**Explanation:**
* **Conversation 1:** This is a typical phone call scenario. 'Could I speak to...' is a polite way to ask for someone. 'Who's calling, please?' is a standard question to identify the caller. 'Putting you through' means connecting the caller to the person they want to speak to.
* **Conversation 2:** 'He left a message on my voicemail' indicates the caller wants Mr. Fallow to return their call. 'Out at the moment' indicates Mr. Fallow is not available. Asking to 'call you back later' is asking him to return their call at a later time.
* **Conversation 3:** The speakers know each other. 'Is that Carlos?' is to confirm they have the right person. 'I couldn't get through; the line was busy' explains why the person didn't call the previous night. 'On the phone' indicates that the person was using the phone and the line was busy because of that.