Deploying Voice over IP (VoIP) successfully in a data network has some unexpected pitfalls. In previous papers, we’ve explored how to do a Voice Readiness Assessment [1] and looked at focused planning and design tips [2,3]. This paper describes changes you can make to improve how a data network handles VoIP traffic – that is, how you can reduce one-way delay, jitter, and data loss for VoIP traffic, while retaining the performance of your other business-critical network applications.