Many companies train their telephone operators to greet all callers in a tone of voice that radiates interest and enthusiasm. The caller feels the company is concerned about them. - Dale Carnegie, How to Win Friends & Influence People
Here are a few tips for having success on the phone:
Believe it or not, people can sense you smiling through the phone. (The next time you call a company, pay attention to whether or not the person who answered the phone is smiling.)
When you are talking to a customer on the phone, stand up. Your energy level is naturally heightened as you are standing. This skill has been used for years by those who successfully make their living on the telephone. TRY IT!
Never make or take a business call unless you are prepared to do so. You will waste a client's time if you call them without a concise and effective purpose for the call. Likewise, make sure that when you take a customer's call that you are not distracted by outside influences. Just like they can tell when you are smiling (or not), people also know when they do not have your full attention.