The session initiation protocol (SIP) is a unifying protocol for providing integrated telephony and Internet types of services, such as Web, presence, instant messaging, and chat. To provide for the integration of these disparate types of services, considerations must be given from a network point of view. However, little attention has been given in the literature to identify the network elements required to provide these services or the mechanisms for integrating these different types of services for end users. This paper describes a network-level services architecture for SIP, including network functions and entities needed to support the services integration. We will discuss how services can be incorporated at different levels in the network, and the types of services typically created at each of these levels. We will also describe a service access and mediation function, which blends disparate types of services in creating a seamless and rewarding user experience.