Page 117 - Intelligent Communication Systems

98 INTELLIGENT COMMUNICATION SYSTEMS
where C is conditional and T and R are actions. C comprises a state description
and an event. T comprises the terminal to be charged and the domain to be charged.
R is a fee. Here are some examples.
Example 1: A call forwarding variable is defined at terminal B. As mentioned
earlier, a call between terminal A and terminal B is charged to terminal A and a
forwarded call between terminal B and terminal C is charged to terminal B, where
the fee is rl. The charge policy is then described as follows:

IF m-cfv(B, C), dial(A, B) THEN A(A-B), B(B-C), rl,
where m-cfv(B, C) means that a call to terminal B is transferred to terminal C when
terminal B is busy.
Example 2: For conventional phone calls, when terminal A calls terminal B,
then the call is charged to terminal A. The charge policy in this case is described
as follows:
IF dial(A, B) THEN A(A-B), r2.
In general, rules that come into conflict are shown here. The following rules
are given:
Rule (1) IF S1(A, B) E1(A, B) THEN B(A-B), rl.
Rule (2) IF S2(A, B) E1(A, B) THEN A(A-B), B(B-C), r2.
For event El (A, B), there are two rules, and the system cannot select one of them.
Therefore these two rules have to be rewritten to resolve the conflict.

9.7 HIGH-LEVEL DESCRIPTION OF TELECOMMUNICATION
SERVICES

(1) A basic function of telecommunication services is to connect or
disconnect a line for a terminal.
(2) Telecommunication services are described in state transition rules as
follows:
Condition (state 1, action) and result(state 2)
When a terminal is in state 1 and action is taken, state 1 is transferred to state 2.
(3) The state of the terminal is defined as follows.
State of service subscription: subscribed/not subscribed
State of service activation: active or inactive
Line state: connecting, holding, or disconnecting
Terminal state: active or inactive
Response from service: response by user number or command input
Relation among terminals: person-to-person call, call forwarding
variable, or 3-party call