congrats on the interview! and the best of luck!

most places now are asking for circumstantial responses - they ask a question, and want a response with regard to:
Situation
Response &
Outcome

so they ask something, want to know "what" your scenario is, "how" you dealt with it, and the result - whether it worked, didn't work etc...

antheia has given some great advice about confidence in your voice - smile, let them know you're interested by sounding enthusiastic and not bored - they can't see you, but it is worth behaving in a similar manner while you're on the phone as you would in a face to face interview - it comes across in your voice if slouching as opposed to sitting up and taking notice.

don't be afraid to ask questions - if they say something, and you're not sure, ask them to repeat it - some questions can be difficult to decipher what they're after. ask about the things you're interested in - hours of work, conditions - whatever takes your fancy!

again - Good Luck!!