IVRS- INTERACTIVE VOICE RESPONSE SYSTEM
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INTRODUCTION
IVRS is an important development in the field of interactive
communication which makes use of the most modern technology available
today. IVRS is a unique blend of both the communication field and the software
field, incorporating the best features of both these streams of technology. IVRS
is an electronic device through which information is available related to any
topic about a particular organization with the help of telephone lines anywhere in
the world.
IVRS provides a friendly and faster self service alternative to speaking
with customer service agents. It finds a large scale use in enquiry systems of
railways, banks, universities, tourism, industry etc. It is the easiest and most
flexible mode of interactive communication because pressing a few numbers on
the telephone set provides the user with a wide range of information on the topic
desired. IVRS reduces the cost of servicing customers.
HARDWARE SECTION
1. Relay: For switching between the ring detector and the DTMF decoder.
2. Ring detector: To detect the presence of incoming calls.
3. DTMF decoder: To convert the DTMF tones to 4 bit BCD codes.
4. Micro controller: To accept the BCD calls, process them and transmit
them serially to the PC.
5. Level Translator: To provide the interface between PC and micro
controller.
6. Personal Computer: To store the data base and to carry out the text to
speech conversion.
7. Audio Amplifier: To provide audio amplification to standard output and to
act as a buffer between the telephone line and sound card.
OPERATIONS OF IVRS
The user dials the phone number connected to the IVRS. The call is
taken over by the IVRS after a delay of 12 seconds during which the call can be
attended by the operator. After 12 seconds if the ring detector output is low, it is
ensured that the phone has not been picked up by the operator. The
microcontroller then switches the relay to the DTMF and sends a signal via RS
232 to the pc to run the wave file welcoming the user to the IVRS. The user is
also informed of the various codes present in the system, which the user dial in
order to access the necessary information.
Thirty seconds are given to the user to press the codes, failure of
which results in switch back of the relay. The DTMF decoder converts the codes
pressed by the user to BCD. It is then pressed to the input pins of the
microcontroller and is stored in the microcontroller memory. After these codes
have been received, they are transmitted serially to the serial port of the PC via
max232 IC. Any hardware failure in transmission falls in the lightning of a LED
and the relay is switched back.
The serial port of the PC is continually polled by the software used
such as Visual Basics and Microsoft Agent program and the received code words
are put in the text box from the input buffer. The received personal identification
number (PIN) is compared with the stored data base to determine the result. The
corresponding wave file is played by the sound blaster card. It is coupled to the
telephone line through the Audio Amplifier, which is connected between the
sound blaster and the telephone line to amplify the blaster output, drive the
telephone line acts as the buffer for sound blaster.
THE ROLE OF MICRO CONTROLLER
The 8751 is the heart of the IVRS system. It controls the operation of
various parts of the IVRS system. When a telephone call is detected by the ring
detector, the micro controller switches the relay to the DTMF and sends a signal
to the PC via RS 232 to run the wave file welcoming the user to the IVRS. The
number given by the user is decoded by the DTMF IC and is stored in the
memory of the microcontroller. The code stored in the microcontroller is send to
the serial port. If any hardware failure occurs, it is the microcontroller which is
taking necessary measures. The IVRS system makes use of a stand by computer
so as to working 24hrs a day for customer satisfaction. In these cases the
microcontroller switches from the first computer to the second.
THE BASIC FEATURES
A microcontroller is meant to read data, perform limited calculations
on the data and control its environment based on those calculations. The
microcontroller consists of an 8-bit CPU in addition to RAM of 128 bytes, ROM,
parallel I/0, serial I/0, counters, clock circuits etc, the EEPROM has a memory of
0 to 4kb. There are four register banks with 8 registers each. The control registers
used are TCON, TMOD, SCON, PCON, IP and IE. The program counter is 16
bit while the status word and stack pointer is 8 bit. The 8751 has 4 parallel I/0
ports. Hence the dual ports of these may be used as general I/O digital lines.A
system clock generator using an external crystal and two external capacitors provide the required clock for the microcontroller. There are 5 INTERRUPT
sources used by 8751 and each can be listed under any of the priority levels. The
5 interrupts are listed below.
RING DETECTOR
The ring detector is connected directly to the telephone line through
the relay which is controlled by microcontroller (8751). The function of the ring
detector is to detect if the telephone is ringing or not.
The ring detector consists of op-amp LM 311 which acts as a
comparator to convert 98 V (rms, 130 Vpp) ring signal to –5V (low level) step
signal for the microcontroller’s INTO pin. The output of the comparator goes
high when the operator picks up the telephone provided along with the IVRS.
The presence of the ring detector output for 5 sec enables the micro controller to
switch the relay to the dual tone multi frequency (DTMF 8870). The capacitor
C1 blocks incoming DC and resistors RA and RB are the voltage dividers to
reduce the incoming voltage of 13VPP to 15V. Diode D passes only the positive half of the sine wave during which C2 gets charged to maximum value and acts
as the DC value for the input signal which triggers the comparator. This charge
does not get discharged easily due to high resistance R3, R4 and R5 are used as
voltage dividers to provide reference voltage of 2.5V to pin 2 of LM 311.
SPEECH ENABLED-IVRS
Today IVRS applications allow self service to automated bank,
account information, airline schedules and movie times. Automated speech
recognition enhances the flexibility and power of IVRS applications. Today
IVRS system can be mode more attractive by replacing the touch tone interfaces
with speech enabled applications. Some applications recognize a very limited set
of spoken letters and numbers that primarily represents the touch key pad. Most
advanced application can enable recognition of more complex phrases and
sentences spoken in conversational manner at a natural speed. With this speech
enabled IVRS systems, the caller can obtain information and perform
transactions by natural speaking.
The addition of speech recognition capabilities provides opportunities
for incremental revenues, increases the variety of automated service delivered
over the telephone and increases the demand for telephony equipment just as
interactive touch-tone applications fuelled the development of new businesses;
speech recognition is creating new opportunities for imaginative entrepreneurs.
CONCLUSION
Interactive Voice Response System has been the latest technology,
each provides the foundation for providing convenient new IVRS services for
customers as well as reduced operational costs, improved customer satisfaction
and retention, increased return on investment and a stronger market presence for
the IVRS services provider. A speech interface gives caller more flexible
navigation outputs that are less complex and more rigidly hierarchical touch tone
menu options.
IVRS can be used in organizations to know about various
departments, mode of working and levels of control. Hardware circuitry of IVRS
is very compact and it can be used as a card in computer. By the wide spread of
internet it is possible to know information from anywhere in the world with the
advanced features of Interactive Voice Response System.