Page 104 - Intelligent Communication Systems

86 INTELLIGENT COMMUNICATION SYSTEMS

(3) Design of the program structure
(4) Programming in C language and debugging
In process (1), the telecommunication service is designed. In process (2),
description by signal sequence or SDL is performed, depending on the design
sheet. In process (3), the program structure is designed according to the descrip-
tion. In process (4), programming is done and the programs debugged. An exam-
ple of the signal sequence is shown in Figure 9.1. In the figure an offhook signal
is issued from the user to the system. The system asks the user which number is
to be called, the user responds by giving a number, in this case 03-5286-3830,
and the system reconfirms the number to the user. The calling process is per-
formed in this manner. The example is described in SDL in Figure 9.2. The ini-
tial state is the idle state. The user picks up the phone and the system asks which
number to call. The system waits for a response from the user. The user inputs the

FIGURE 9.1 Example of signal sequence.