# NCC API functions

ISDN Software invokes NCC API functions to perform call control. For most of these functions, one or more events are returned in response to the invocation.

There are two types of events associated with call control operations:

Event type | Description
Solicited | Signify acknowledgments from the API or the TCP, or occur as a consequence of some function call.
Unsolicited | Can occur at any time, regardless of the application's current activities. Usually, unsolicited events indicate that something has happened on the line.

Certain NCC.START and NCC.X.ADI_ISDN.START parameters dictate whether certain informational call control events are generated. For detailed information about NCC.START parameters, refer to the Dialogic® NaturalAccess™ NaturalCallControl™ API Developer’s Manual. For information about NCC.X.ADI_ISDN.START parameters, refer to ISDN TCP parameters overview.

For information about the NCC API call control-related functions, refer to Call control functions and solicited events.

For detailed documentation of the NCC API functions, parameters, and events, refer to the Dialogic® NaturalAccess™ NaturalCallControl™ API Developer’s Manual.