Abstract: A system and method for providing Value-Added Services (VAS) in an integrated telecommunications network having a packet-switched network portion (PSN) operable with Session Initiation Protocol (SIP). The integrated telecommunications network includes a SIPext SSP server, a trigger server, and a service node having a Service Logic Program (SLP) that is operable with Intelligent Network Application Protocol (INAP). The SIPext SSP and service nodes are provided with the capability to communicate using SIP-compliant messaging. New header fields are provided that specify operations to be performed by the service node with respect to a service. INAP service parametric data is also provided in the header fields in a sequential form. When a call is received in the SIPext SSP server for a user having a subscription for a VAS, it queries the user profile stored in the trigger server.