It's hard to get in to see people these days. The way you present yourself on the phone is very important to being a successful freelancer.
What you have to communicate quickly is several important points:
1- You can help the person.
2- You can help the person.
3- You can help the person.
People aren't calling you because they think you are the best designer in the world. They are calling you because they have a problem and they are hoping you are the person that can solve that problem.
No matter who calls you, their problem is the same: they need to SELL a service or product. How you are going to do it is the solution to their problem... it could be a sell sheet, or a logo that communicates a deeper meaning, it could be an ad, a flash banner or a new web site maybe a postcard.
You should be nimble and you should be able to offer lot's of different graphic design answers... not just the ones that they are looking for.
Imagine going to a car dealer and telling them that your problem is that you need to be moving large boxes across town every day. If they only sell race cars, they will be only recommending a race car to you.
As a successful freelancer you have to have skills in a wide area so that you have different revenue streams... that's your "toolbox" to help your clients.
Bottom line: your job is to SELL your clients service or product. The more design areas that you are skilled in the better chance you have of helping your client and making a better living.