# Fusion and the CG 6565C board

Gateway applications provide a way of transferring data between telephone network and packet network interfaces. Fusion 4.21 or later provides software for developing IP telephony gateway applications that run on CG boards. For more information about Fusion software and Fusion CG 6565C board configurations, refer to the Dialogic® NaturalAccess™ Fusion™ VoIP API Developer's Manual.

Fusion 4.0 (or later) configurations use CG boards to receive and transmit data to PSTN and to IP networks. Fusion applications use NaturalCallControl API (NCC API) functions to place and receive PSTN calls, and Media Stream Protocol Processing API (MSPP API) functions to create and configure media channels between PSTN and IP networks. For more information about MSPP service functions, refer to the Dialogic® NaturalAccess™ Fusion™ Media Stream Protocol Processing API Developer's Manual.