5.1 INTRODUCTION AND OBJECTIVES
One of the major changes IP-based technology offers for telephony is call processing
applications. Many of the telephony services typically depend on a user??™s status and
their creation does not necessarily require intermediary organizations. In fact, the cost
of their production would be less if they were made closer to their user. To illustrate the
Domain-Speci?¬?c Modeling: Enabling Full Code Generation, Steven Kelly and Juha-Pekka Tolvanen
Copyright # 2008 John Wiley & Sons, Inc.
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application development, let us look at some of the typical telephony services
illustrated by Lennox and Schulzrinne (2000):
. Call forwarding if the receiver is busy or does not answer: For instance, when a
new call comes in, the call should ring at the user??™s desk telephone. If it is busy,
the call should always be redirected to the user??™s voice mail box. If, however,
there is no answer after four rings, it should be redirected to the user??™s voice
mail unless it is from a supervisor, in which case it should be proxied to the
user??™s cell phone if it is currently registered.
. Information address service: An example service could be made for a company
that advertises a general ???information??? address for prospective customers.
When a call comes in to this address during of?¬?ce hours, the caller should be
given a list of the people currently willing to accept general information calls.
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