To describe the modeling languages consistently and precisely, we will use the
metamodeling language documented in Appendix A.
The modeling languages, generators, and example models from Part III can be
downloaded from http://dsmbook.com along with a free MetaEdit+ demo.
96 TELEPHONY AND CALL PROCESSING
CHAPTER 5
IP TELEPHONY AND CALL
PROCESSING
In this chapter we describe DSM solution made for specifying Internet telephony
services. Recently multiple protocols, such as SIP (Rosenberg et al., 2002) and H.232
(ITU, 2003), have been de?¬?ned to provide a session initiation protocol for telephony
over IP networks. These protocols also offer the possibility to decentralize the control
of user-speci?¬?c call processing services. In traditional telephony systems, networkbased
services were created only by the service providers, such as operators. Service
creation has required special knowledge of the telephony system in use and use of a
variety of often proprietary tools, and most importantly many of the user-speci?¬?c
service customizations were simply not available. Internet telephony changes this as
protocols are open and allow even telephony users to de?¬?ne their own customized
services. Here, aDSMsolution is created to alloweasy speci?¬?cation of call processing
services using telephony service concepts.
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