Telecom networks are rapidly developing the ability to support voice and data calls. Converged networks that bring together wireless, wireline, and IP networks will have the ability to offer sophisticated combinations of voice and data transmissions. The key to success in these networks rests in the creation of innovative services and applications. To this end, network operators are opening their networks to third-party developers for the first time in their more than 100-year history. This is accomplished using open Application Programming Interfaces (APIs) that allow outside access to these networks.

The mere existence of these APIs in the telecom sphere is revolutionary. Until now, telecom networks have operated as "closed shops" because of their extreme complexity. The rapid changes occurring in both the technical and business landscapes of this world require shorter development and release schedules in order to achieve success.

The book is intended for programmers, researchers, engineers and managers who will be dealing with converged networks and have a good working knowledge of object-oriented programming. A familiarity with Java and XML will also be helpful.

The first third of the book is devoted to explaining the history and functionality of telecom networks in a way that will be clear to developers more familiar with datacom. This section alone is worth the price of the book because it takes an extremely complex subject and presents it in a clear, straightforward fashion. The authors' style is clear, concise and makes use of simple, real-world examples to illustrate their concepts. Most examples are presented from the user's perspective, which keeps the subject grounded in reality.

The majority of the book focuses on call control, which is described as "the process of creating, manipulating and terminating communications sessions." The authors apply this definition to data communications sessions, as well as voice communications.

The Java Telephony API, Java APIs for Integrated Networks (JAIN), and the Parlay/Open Services Access are all examined in detail in separate sections. The history and intentions behind each API is presented followed by a detailed description of their functionality. A real-world example application, with detailed explanations of the code behind it, is presented at the end of each section. In several cases, the same functionality is created using each API. This is a real plus because it exposes the differences and similarities between the various APIs.

The book concludes with a look at issues common to all the APIs and then gives a brief overview of the growing use of XML in call-control applications.

This book is useful as an introduction to the world of telecom application development and the sections should be read cover to cover.

By John Maxwell Hobbs