For office procedures, I recommend you start off with Office 5S and Kaizen before using 6 Sigma. I have successfully used both at work and home office.
1. Office Kaizen: Transforming Office Operations into a Strategic Competitive Advantageby William Lareau
2. Visual 5S and Lean Office (Productivity Inc)
Benchmark with ASQ Call Center in their Milwaukee offices. You can set up a time and they will share a whole load of best practices that you can implement right away.. Let me know if you need additional help.