Page 68 - Intelligent Communication Systems

52 INTELLIGENT COMMUNICATION SYSTEMS

~0120-xxxxxx 1)3-5286-3000 Toll-Free Phone
Directory DB

/\ Network -/\

FIGURE 7.1 Toll-free phone system.

7.1 TOLL-FREE PHONE SERVICE

Toll-free phone service shifts the charges for a call to the destination, whereas tele-
phone charges are usually made to the source. In Japan the prefix for a toll-free
call is 0120; in the United States it is 800, 888, 877, or 866.
When a toll-free phone call is initiated, the system recognizes it as such,
accesses the database of toll-free phone numbers, translates it into a destination
number, and then switches the call to the destination (Figure 7.1).
The volume of toll-free phone calls is increasing every year. For example, in
the United States the volume of toll-free calls has already exceeded that of the con-
ventional calls. In other advanced countries, the number of toll-free phone calls is
increasing rapidly.

7.2 CALLER ID SERVICE

The ISDN basic user network interface has two B channels and one D channel.
Using the D channel, the caller's ID can be transmitted to the destination and dis-
played on the screen of the telephone. Thus, before answering the phone, the called
party can see what number is calling, thereby allowing the called party to decide
whether or not to answer the call.
Currently it is the caller's phone number that is displayed on the screen. This
makes it difficult to identify the caller in a short time. It would be more desirable
to show the caller's name on the display screen. Common carriers in Japan are
currently investigating technology for translating a phone number into its sub-
scriber's name in real time. To achieve this, a database consisting of a table of sub-
scribers" names with their phone numbers has to be constructed and accessed in
real time.