# Fusion defined

The NaturalAccess Fusion VoIP API consists of hardware and software for producing IP telephony gateway applications and media server applications.

Gateway applications provide a way of transferring data between endpoints created at telephone network and IP network interfaces. These applications convert voice and fax data as they transfer it from network to network. For example, when a gateway transfers voice data between a PSTN and an IP network, it converts the data between PCM and data packet form and (when applicable) encodes and compresses the data. The data can then be switched over traditional telephone networks, sent over IP networks to compatible computer client terminals, or directed to other gateways.

The following illustration shows two Fusion gateway systems transferring voice and fax data from one PSTN, over an IP network, to another PSTN:

## Fusion media server applications

Fusion media server
applications perform media processing and IVR
tasks such as providing voice prompts, detecting and generating DTMF digits, or using speech recognition to query or deliver information. Fusion media server systems do not need to be connected to a PSTN and may instead only receive voice data from an IP network (through a Fusion gateway system or directly from a client application such as NetMeeting).

The following illustration shows a Fusion media server receiving voice data over an IP network through a Fusion gateway system: