Many interviewers will ask you to name your strengths and weaknesses. Typically, people find it easier to express their strengths, but struggle when it comes to identifying even one weakness. Part of the reason for this may be that they do not want to disclose a particular weakness, as this may result in them failing to be successful in getting the job.
A good initial answer (bearing in mind you are applying for a telephone position) to the 'strengths' part would be "I have been told that I am an excellent communicator, especially on the telephone, but I feel I have good interpersonal skills generally and find it easy to get along with all sorts of people".
For weaknesses you need to think of something which is really a strength but put it across as a weakness. It is also important to make it clear what you are doing to address that 'weakness'.
A good example would be "I am a very conscientious worker and I get irritated by colleagues who don't share this value and take any opportunity to take time off work or do the minimum required when they are there. I am learning, however, that these people generally get found out and I leave it to my supervisor to recognise these problems and address them".
An answer such as this would probably make the interviewer think "well that's not such a bad thing, actually".