We use "competency" based interviewing here. Its very effective at weeding out liars!
The purpose of it is it effectively gets you to substantiate claims. Asking an open question e.g "what would you do if..........?" means nothing as you can say whatever you like whether you would or not.
The prupose is to for you to substantiate it e.g give me an example of....
Now they may or may not use it on your telephone interview but even if they don't use real examples to illustrate/answer they're questions; It'll give much more credibility.
Also (as you are doing) prepare for teh interview. Think about what skills/person are required for the job. Armed with this you will have some ideas what they may ask. As such you can think about examples to tell them. Like I incraesed sales...... etc
Fact is better than hypothetical
And keep calm, take a moment to think about what they are asking - nothing worse than getting an answer you didn't ask for. If you are unsure ask them to clairify.
Another "trick" often used by interviewers is silence. As the inerviewee you will feel bound to say something. I would imagine this is even worse over the phone! Not much you can do about it but rather than say anything, ask them if you have answered the previouis question to their satisfaction or would they like more detail
Oh and good luck