Advanced Voice & Data has been one of the top 20 fastest growing businesses in the san francisco east bay for the last four years with over 4,000 clients in northern California. .When doing all of our jobs we sometimes over order so this site is created to sell our surplus and lightly used parts. We are located in Concord, CA. AVD has been in business since 1992. I credit this success to pursuing the goal of 100% customer satisfaction. "