Advice of charge information is provided utilizing the session initiation
protocol (SIP) in an Internet protocol multimedia subsystem without
utilizing an application server. The advice of charge message is provided
to a user via the serving call/session control function and the home
subscription server. When a request for a service is received by the
serving call/session control function, the state of a binary, Boolean
flag associated with the originator of the request is analyzed. Depending
upon the state of the flag, either the request is routed to its intended
destination, or an advice of charge message is routed to originating
user, advising the user of the charge for the requested service. If the
user accepts the charge, the serving call/session control function
transmits the request for routing to the intended destination, and the
flag is toggled. If the user declines the charge, the call is ended.