A method is described of facilitating targeted content delivery in a network comprising a service provider network (SPN) and a user profile data database external to the SPN. The method comprises: receiving, from a demand side platform, segment definition data comprising a list of user attributes and corresponding user attribute values associated with a targeted content delivery process; and communicating, to a server, the segment definition data, wherein the server has access to the database, to identify one or more candidate users to be targeted based on matching the user attribute values with user attribute values in the database. The method also comprises receiving, from the server, a list of identifiers, wherein each identifier is usable to identify one or more candidate users to be targeted; and communicating the list of identifiers to an entity in the SPN which is responsible for facilitating the delivery of targeted content.