14.1 Introduction

If you call any large cinema looking for times for films, you will undoubtedly be forwarded to an automated system that tells you when each film is on. This system is made possible by digital telephony.

Computer Telephony Integration, or CTI, systems routinely cost $10,000 and upward for enterprise-scale systems. The high cost is largely a result of the misconceived idea that any telephony system requires loads of specialized hardware and, thus, is out of reach for the humble developer. In fact, you can put a simple system together using no more than a cheap modem.

Any company that employs staff to answer phone calls can save money by implementing a CTI system. Such a system can be used to route calls to different departments automatically or to match a caller with customer ID and associated purchase history.

This chapter is mainly devoted to one rather large code example built up in three sections. The first section explains how to pick up and drop a call. The following section explains how to detect key presses on the remote handset, and the chapter concludes with a demonstration of how to play back audio to the caller.

14.2 Basic Telephony

This chapter is focused on using the telephony API,...