This Recommendation contains the requirements and analysis for the business-to-business (B2B) and customer-to-business (C2B) interfaces of appointment management for NGN. It assumes a multi-service provider environment and is aimed at appointment management to support the deployment of NGN and includes both the B2B and C2B interfaces. Appointment management consists of some processes which include scheduling an appointment, confirming an appointment, updating or modifying an appointment, cancelling an appointment, reporting appointment(s), tracking the history of an appointment and retrieving an appointment. For regulatory oversight, it is assumed that detailed record-keeping will be maintained within the service provider (SP) to support the service level agreement (SLA) or regulatory statute. Third-party request/response operations are dependent upon the privacy business rules defined in the SC's/SP's contract and consequently are considered out of scope for this Recommendation.