uited to more general purpose use with higher perfor- mance and more line ports and disk storage. There are many PC 37.2 Anatomy of a voice processing based products in the market place. One of the benefits claimed for system the PC products is the 'openness' of the platform. This openness is usually only effectively available to companies with experienced In order to understand some of the issues involved in the many programmers. Also, because of the limitations of the platform for applications of voice processing let us examine a generic voice voice processing applications, it may be difficult to incorporate a processing system. This description is not intended to relate to any wide range of features and applications in the same PC. particular manufacturer or model. The callers access the system via the telephone network inter- The diagram above is intended to depict a general voice process- faces. There are two main types of telephone network connection: ing system. In the real world keen attention is payed to the number analogue and digital. The trend is increasingly towards digital of lines supported, the amount of disk storage available and the network connection. This is because of the improved quality, the Telephone Speech network interface compressor Speech Bus Analogue/ digital Converters Voice "Grunt" service applications Speaker processor Verification Computer Bus Figure 37.1 Generic voice processing system architecture 37/6 Voice processing convenience of the physical network connection and the increased Whereas normal human-to-human conversations naturally termi- functionality and reliability possible. nate in the face of silence, human machine conversations do not. Unless the machine has a clear indication from the telephone net- 37.2.1 Analogue network connections work that the caller has gone, it will continue trying to interact with the caller. The procedure usually adopted to overcome this is for the There are four types of analogue network connections: direct dial voice processing system to gi