Disclosed are techniques for optimization of media flows within a provider network. The provider network comprises a plurality of sites, each site having one or more media servers capable of supporting a media session with a user endpoint device. The provider network further includes a media server director (MSD) that receives registration information identifying one or more user endpoint devices that have registered with a particular site. Using this registration information, as well as predetermined preference policies, the MSD prepares a preference order for the media servers of the provider network for user endpoint devices associated with the site. When an application server signals an intent to establish a media session with a user endpoint device of the site, the MSD selects a media server based on the preference order and provides an indicator of the selected media server. The application server can then contact the selected media server identified by the indicator to establish and support a media session with the user endpoint device.