Lean thinking has proved to be successful in improving results in industry. Services could benefit from this approach too. The success of lean thinking depends on the appropriate identification and elimination of waste. This paper describes the work carried out in identifying and analysing waste in the customer service process of a major telecommunications operator. An Action Research approach was adopted, and a "lean team" of company personnel was specially formed to undertake the necessary fieldwork. The study inspired management changes aimed at improving the customer service centreÂ´s performance.