You identify yourself to the other person.
There's an interruption while you're on the phone.
You can't hear the person very well.
The person the caller wants to speak isn't there.
You dialed a 4 instead of a 5.
You want to talk to a different person.
We have a bad connection. Call me back.
This is Kathy Marks.
Could I speak to John please?
Can i take a message.
I'm sorry i have the wrong number.
Just a minute.