One of the most successful ways to build team spirit is to increase employee engagement. There are various tricks you can find, and it's a whole new topic. In short, you work with improving working conditions, providing compensations for overtime, offering career advancement, training, social benefits. You can also introduce some internal customer service awards and implement bonuses for achieving them. Sharing successful case studies also gives motivational effect. Your QA specialist can gather and summarize all positive feedback to teach agents how to achieve it. All these (and other) methods can give your team a necessary boost and inspire your employees.