When I worked for the SEO firm, we had a huge sales floor, and the phones rang off the hook. The sales people were wired to their desk for hours, and unable to get up from their desk and walk around. Once we went to wireless telephone headsets that all changed. They could answer their phone in the lunch room if they wanted to, and they could even be outside on a smoke break, but still talking to a client. Sales people are generally movers, so having the telephone headsets allowed them to stand up, talk with their hands, and make their pitches more effectively.