Automated methods and systems for determining and setting router QoS adjustments to control the service level of VoIP voice communications in a packet switching network supporting both voice and data communications. Network topology and service level requirements are processed to determine QoS settings for each of the routers. The QoS settings are transmitted to the routers, for example in the form of a router configuration file, to set the QoS adjustments to achieve the desired VoIP service level. The invention is applicable to packet switching networks comprising routers or equivalent electronic switches providing electronically adjustable QoS settings.