Microsoft Windows Telephony SDK Q&A

What is the Telephony API?

The Telephony API provides a standard programmatic interface under Microsoft Windows for interacting with telephone networks.  It allows applications developers to write applications that can work on a variety of different telephone networks, such as analog, PBX, ISDN or even cellular.  No more hardcoding to a particular network.  This should facilitate the development of shrink-wrapped telephony products.  It also gives network service providers and hardware developers to write a single driver and take advantage of a broad range of applications.

What is in the SDK?

The SDK includes an implementation of the API developer can redistribute with their products ona  royalty-free basis, complete documentation and sample driver and application source code.

How can I get it?

The Software Development Kit is available electronically on CompuServe (in the Microsoftsymbol 210 \f "Symbol" \s 10 Software Library - GO MSL) and the Internet (via remote ftp at in \devtools\tapi).  Developers attending the Microsoft Professional Developers Conference (December 13-17 in Anaheim, Calif.) will receive a copy of the SDK on CD-ROM (call +1 (800) 233-1729 or +1 (314) 827-5614 to register).

The SDK will also be included on the January issue of the new Microsoft Developer Network (MSDN) Level II platform.  This is a set of four CD-ROM disks that contains all Microsoft SDKs, DDKs and operating systems. This quarterly offering for developers accompanies the MSDN Level I Development Library, which contains all documentation for the development platform (but no code).  To order, call +1 (800) 759-5474 in the US or Canada, +33 05-90-59-04 in France, +49 (130) 81-02-11 in Germany, +31 (60) 22-24-80 in the Netherlands, +44 (800) 96-02-79 in the UK.  For any other country in Europe call +31 (10) 258-88-64.  For other countries outside of Europe or the US and Canda, call +1 (402) 691-0173.

You can address questions or feedback about the Telephony API via the Internet at “” or via fax to “Windows Telephony Coordinator” at +1 (206) 936-7329.

How does this fit into the Microsoft Windows family?

This SDK supports development of Win-16 applications.  The same API will be available across the entire Microsoft Windows product family.  It will be included in the Windows 95.  It will also be implemented on Windows NT (no date announced).  But the API is the same across 16-bit and 32-bit versions of Windows.

How does this relate to Microsoft At Work?

Windows Telephony is is another step in the Microsoft At Work initiative to integrate systems in the workplace and create a new platform for office solutions that span PC and office systems such as the telephone.  It provides an interface between computing devices and telephone networks and will be used both on the PC and in a new generation of telephone devices.

Does this compete with the Novell/AT&T Telephony Services product?

No.  Actually they represent different approaches to different problems and in fact can be complementary.

Windows Telephony is an API that resides on the PC and provides access to a variety of networks through a variety of connection models.  One of the ways to deliver telephone services to the desktop is through something like the AT&T/Novell server product.  There are a variety of companies that offer server products like this (IBM, DEC, etc).  A Telephony API driver on the client could talk to the AT&T/Novell server for telephony control..

The AT&T/Novell product:

AT&T has also endorsed the Windows Telephony API.

Doesn’t AT&T have a rival interface with PassageWay?

AT&T’s PassageWay product is a hardware interface to their PBXes.  It provides a physical connection to the PC.  They have announced they will support Windows Telephony as the software interface for this hardware.  In fact, they demonstrated their Telephony API driver for PassageWay at COMDEX.

How does this compare with what Apple is doing?

Apple had an API that was similar in scope called the Telephone Manager.  They seem to have abandoned this API recently, probably because there are very few applications that exploit it (less than 5).  Their recently announced Macintosh AV machines include a physical interface called GeoPort that gives access to analog telephone connections.  However, they offer no API for this port, so developers can’t take advantage of it.

How will Microsoft support this API in its applications?

You can expect us to support this technology in a variety of applications where it makes sense.  For example, we showed Microsoft Word using the Telephony API at COMDEX.

What is Intel’s involvement?

Intel and Microsoft developed the original specification.  The two companies often work together to advance the PC platform. 

Who supports it?

A broad range of companies have announced their support for the API, including:

Active Voice Corporation
Alcatel Business Systems Group
Analog Devices
Articulate Systems
AT&T Global Business Communications Systems
Bell Atlantic
Centigram Communications Corporation
Compaq Computer Corporation
Contact Software International
Cypress Research Corporation
Digital Equipment Corporation
DSP Group, Inc.
Ericsson Corporation
Floreat, Inc.
Fujitsu Business Communications Systems
Harris Corporation
InteCom, Inc.
Jensen-Jones, Inc.
Lotus Development
Motorola Digital Signal Processor Operation
National Semiconductor, Inc.
Natural MicroSystems
NEC Corporation
Northern Telecom
Octel Communications Corporation
OCTuS, Inc.
Polaris Software
Rockwell International Corporation
Siemens Private Communication Systems Group/ROLM
Sequent Computer Systems, Inc.
Smart Technologies
Stylus Innovation
TeleInt GmbH
Unifi Communications Corporation
US West Communications, Inc.
VMX, Inc.
Voice Technologies Group, Inc.

Copyright 1994