For many organizations, connectivity between computer and telephone systems is a key initiative. There are many benefits in terms of integration and additional functionality. Computer telephony solutions offer a means to full integration between network operating systems and a traditional PBX-style telephone system. This document will evaluate each network operating system’s on integrated telephony capabilities. It will also evaluate each system’s ability as an extensible platform on which software developers can build customized solutions.
Solaris 7 Implementation Details
Solaris 7 offers no telephony protocol or API support as part of the operating system at this time, requiring the use of other operating systems or third party solutions for telephony support.
Windows NT Server 4.0 Implementation Details
Windows NT Server 4.0 represents Microsoft’s entry into telephony-enabled operating systems. Telephony support is provided by the inclusion of Microsoft Telephony API (TAPI) 2.0 as part of the operating system. TAPI 2.0 abstracts the hardware layer, providing customers with freedom and device independence. Using TAPI 2.0, developers can easily write applications for use on PSTN, ISDN, PBX, and IP networks. A set of Microsoft ActiveX controls, such as the Visual Call Control, are included with the TAPI 2.0 implementation to provide developers with a starting ground, further simplifying and accelerating the process of creating telephony-enabled applications.
Because TAPI 2.0 is integrated with Windows NT Server 4.0, it has a lower cost of development and ownership than proprietary telephony solutions because it can leverage the extremely large installed base of Windows developers and users and the associated support networks. Additionally, TAPI-derived solutions have the benefit of being able to fully integrate with the Windows operating system and Windows-based applications themselves – something that is not achievable with other proprietary telephony solutions.
Windows 2000 Server Implementation Details
Windows 2000 Server features full telephony support in the operating system, improving on the foundation in Windows NT Server 4.0. Full support for the next-generation Telephony API (TAPI) 3.0 and the ITU H.323 electronic conferencing protocol is provided. Additionally, Windows 2000 comes with an integrated Dialer application and the Microsoft NetMeeting® electronic conferencing software, providing rudimentary applications in the box that can easily be used as the basis for developing and deploying more sophisticated telephony applications. TAPI 3.0 provides the basis to unify IP and traditional telephony to enable developers to create a new breed of powerful telephony-enabled applications.
Usage scenarios abound for TAPI 3.0-based telephony applications running on Windows 2000 Server, especially when combined with other operating system features such as Active Directory, Windows Media Services, Microsoft NetMeeting, or Information Locator Services. Possible scenarios include using Windows 2000 Server as a call control platform, as a platform for an open PBX, to network enable traditional PBXs, to support voice over data networks, or to integrate voice and video dialing.
In the call control scenario, TAPI 3.0 can be used to build integrated streaming media and call control services solutions. These solutions can create sophisticated Interactive Voice Response (IVR), Intelligent Automatic Call Distributor (ACD), and skills-based routing solutions. Connecting a Windows 2000 Server with a PBX using these services creates a complete solution to allow customers and employees to access electronic information by phone.
Windows 2000 Server also makes an excellent, full-featured platform on which to build an open PBX-based system. An open PBX allows the customer to consolidate voice services and telephone switching into a single platform, thereby reducing the cost of integrating telephone and data networks. By simply adding telephone-switching cards to an open-standard PC platform with Windows 2000 Server, customers can glean the full benefit from a cost-effective, network-integrated PBX.
Traditional PBX systems can also be fully extended with Windows 2000 Server and TAPI 3.0. Authentication, security, user policies and phone directories can all be integrated between the PBX and Windows 2000 Active Directory. By installing Windows 2000 Server on a card within the switch, the telephone switch can integrate with data networks and take advantage of the open programmable network infrastructure of Windows 2000 Server. For example, telephone switches can integrate network-based call control features without the complexity of an external call control server. User policies for telephone access could be integrated with Active Directory to unify control of telephone and data services. Finally, the switches can use the integrated media stream services of Windows NT Server 5.0 to simplify scalable voice services.
Voice-over-data is another capability of Windows 2000 Server telephony support. Integrated ITU H.323, QoS, and CoS features provide a solid foundation for interoperable voice-over-IP with the ability to reserve bandwidth and prioritize traffic to guarantee audio quality. These capabilities are used by Windows Media Services and Microsoft NetMeeting and they can be applied to third-party voice and telephony solutions.
Finally, the Windows 2000 Server integrated dialer application, which uses TAPI 3.0, ITU H.323, and the Information Locator Services, can deliver a unique desktop dialing solution. The dialer provides Windows-based telephone handset and call control for dialing, answering and forwarding when used with TAPI integrated phones or switches. The dialer can also be used to place voice-over-IP calls to any dialer-enabled system in the network, using a simple microphone and multimedia speaker system connected to the system running Windows 2000. Calls can be easily conducted, with other people in a company, whenever a user is logged into the network, including remote users over VPN and RAS connections. By adding an inexpensive video camera to the Windows 2000-based PC, users can add videophone functionality. The Information Locator Service can also be configured to arrange conference calls using the dialer. The dialer solution can be further extended with other H.323 compliant applications, such as Microsoft NetMeeting, to add additional functionality. Finally, standard calls through the Public Switched Telephone Network (PSTN) can also be added to the solution with a voice-over-IP to PSTN gateway.
Telephony Services Summary
For customers seeking to integrate their network operating system with their phone system, Solaris 7 represents an unrealistic choice. Telephony support or integration features are not present in the operating system at all. Where telephony is a priority, Windows NT Server 4.0 or Windows 2000 are the only feasible choices. Of the two, Windows 2000 Server is the better choice, as its implementation of the Telephony API (TAPI) is an entire generation newer than that present in Windows NT Server 4.0, offering a considerable amount of additional programming flexibility. Windows 2000 Server is also better equipped to serve telephony applications. It contains numerous networking enhancements, such as QoS or CoS, that are of considerable benefit to voice or TAPI-based applications. Finally, the addition of the integrated Dialer application and ITU H.323 electronic conferencing protocol support provide in-the-box applications to allow customers to get started developing and deploying their telephony solutions.