# Other components

In addition to the ISDN Software, you need the following components to build an ISDN protocol application:

- One or more T1, E1, or BRI trunk interface boards.

- NaturalAccess.

Warning: | Dialogic obtains board-level approvals certificates for supported countries. Some countries require that you obtain system-level approvals before connecting a system to the public network. To learn what approvals you require, contact the appropriate regulatory authority in the target country.

## NaturalAccess

NaturalAccess is a complete development environment for telephony applications that must be installed to build an ISDN Software application.

For more information, refer to NaturalAccess environment.

## NaturalCallControl under NaturalAccess

The NaturalCallControl API (NCC API) features a protocol-independent API, separate call and line state machines, call hold/retrieve capabilities, and the ability to query a protocol's capabilities. Use this service to perform call control operations.

For more information, refer to the Dialogic® NaturalAccess™ NaturalCallControl™ API Developer’s Manual.