National Semiconductor Corp is shipping the first call control service provider software for local area network-connected personal computers based on Microsoft Corp’s Telephony Aplication Programming Interface. The software is integrated with NatSemi’s isoEthernet AT Adaptor boards, now shipping through its OEM customers. It is designed to enable high performance, real-time, interactive multimedia applications and provides a system capable of supporting all current and future third party developers’ Telephony Application Programming Interface-enabled applications for Windows 3.1, Windows for Workgroups and Windows95. There are two key applications, said Duncan Greenshields, the company’s market development manager. The first is computer-telephony integration and the second is real-time multimedia. It gives you the ability to send real-time speech and other data at the same time as Ethernet traffic. The call control software runs entirely on a personal computer’s processor and interfaces to the interface service provider interface. This enables existing applications that are compliant with the interface to interface to networking hardware such as isoEthernet, ISDN and Asynchronous Transfer Mode. The software is modular, to increase flexibility. A call control module implements real-time signalling and bandwidth management for ISDN, Asynchronous Transfer Mode and isoEthernet, while a call driver and data link manager provide the links necessary to ensure guaranteed delivery of call control messages. An operating system-independent hardware abstraction layer provides a means of concluding the link to the network signalling channel. The company said extensive interoperability tests have been conducted with a variety of products, and that the Telephony Application Programming Interface-based call control has been verified against Windows NT, Unix, OS/2 and Apple Mac OS-based call control, call server and hub products.