The following phrases are used when you’re on the phone.

Hello, I’d like to speak to Mr…
Hello, this is Miss…calling from…
Is Ms…available, please? My name’s…

Speaking.
I’m afraid he’s in a meeting/not in the office/still at lunch/not available just now. Is there anything I can do for you?
Hold on a moment, please.
I’ll just find out if she’s back yet/in the other office/available.
I’ll put you through to Miss…
I’ll ask her to call you back as soon as she’s free.
What’s your extension number/fax number?

Could you ask her to call me back, please? My number is…
Could you give him a message, please?
What time do you expect her back?
I’ll call again later today.
Thanks very much for your help.

Requesting

I’d like you to…, please.
Could you ask… to …for me?
Do you think you could…?
Would you mind…-ing…?

Sure.
Certainly.
I won’t be able to…, because…
I’m sorry but…
I’m afraid that’s not possible, because…

Offering to help

Can I give you a hand?
Would you like a hand with…?
Shall I…?
Would you like me to…?
If you need any help, just let me know.

Yes, please. Thanks a lot.
No, thanks, I think I can manage.
That’s very kind of you, but…
I think I’d prefer to do that myself because…