Telecommunication system and method enabling a user to get access to an automated call processing from a central station operating on pulse dialling mode

The present invention is related to a telecommunication system and method enabling a user to get access to any of automated call processing systems. The system comprises in combination a telephone line interface means adapted to provide function of a telephone set, a control means connected to the telephone line interface means, and adapted to constantly monitor the telephone line, analyze a call progress and a ring back tone signals and to switch automatically without human intervention from a pulse dialling mode to a DTMF dialling mode upon detection of a ring back signal validated by a central office. This system also includes a handset and keypad means connected to a telephone interface means and the control means. The central office processes calls in a pause dialling mode. The system enables the user to get access to automated call processing systems, the access to which is limited only to callers equipped with a DTMF telephones and central office base DTMF services. The telephone interface means are adapted to detect the presence of a ring signal on the telephone line, wherein the ring signal is indicating a receiving call mode. The control means are adapted to detect the presence of a ring back signal, wherein the ring back signal is indicating a placing call mode.

The present invention is related to a telecommunication systems and more 
particularly to systems enabling to automated call processing systems, 
such as voice mail tele banking, voice response etc., via central offices 
operating on pulse dialling signals. 
There is known U.S. Pat. No. 4,675,902 related to a high performance 
telephone instrument with combination pulse and tone dialling capacity. 
The circuitry permits the placement of a call through a rotary dial only 
system into a second network that is of a tone only nature. 
There is also known U.S. Pat. No. 5,228,079 related to a method and 
apparatus for pulse/tone detection and selection comprising pulse and tone 
generators connected to a telephone network, selecting device and a 
controller in communication with said selector for causing said selector 
to select one of said generators. 
There is also known U.S. Pat. No. 3,959,599 related to a call initiation 
delay arrangement for digital data switching system comprising means 
responsive to call initiating signals from each calling line for 
requesting the services of the common control equipment. 
At the present time, the convenience that call processing technology 
(audiotex programs, voice mail and voice response, etc.) has provided 
people is indispensable. However those systems can be addressed only with 
DTMF signalling, creating a barrier for the pulse telephone user to 
experience the benefits of the technology. 
The source of this barrier lies in the central office (COs), since some COs 
can process calls in pulse dialling mode only. Calls which are placed with 
DTMF signalling will not go through and therefore will inhibit the user to 
access the voice mail application. 
The present invention solves this problem and presents a telephone set 
equipped with special circuitry capable of switching between pulse and 
DTMF or tone dialling modes automatically. 
SUMMARY OF THE INVENTION 
Broadly, the present invention comprises a telecommunication system 
enabling a user to get access to any of automated call processing systems, 
said system comprising in combination: 
a telephone line interface means adapted to provide function of a telephone 
set; 
a control means connected to said telephone line interface means and 
adapted to constantly monitor the telephone line, analyze a call progress 
and a ring back tone signals and to switch automatically without human 
intervention from a pulse dialling mode to a DTMF dialling mode upon 
detecting validated by a central office said ring back signal; and 
a handset and keypad means connected to said telephone interface means and 
said control means; 
wherein said central office processes calls in a pulse dialling mode, and 
wherein said system enable the user to get access to said automated call 
processing systems which access is strictly limited only to callers 
equipped with a DTMF telephone and a central office base DTMF services. 
Said telephone interface means are adapted to detect the presence of a ring 
signal on said telephone line, wherein said ring signal is indicating a 
receiving call mode, and said control means are adapted to detect the 
presence of a ring back signal, wherein said dug back signal is indicating 
a placing call mode. 
In another embodiment, said control means comprises: 
a microcontroller means and 
a differential amplifier means. 
Said telephone line interface means comprises: 
a microprocessor and 
a pulse dialling means. 
In yet another embodiment, said microprocessor means further comprises a 
DTMF generator means adapted to provide the DTMF dialling mode, and said 
differential amplifier means is connected to the telephone line and is 
adapted to detect the presence of the ring back signal. Said 
microcontroller means is adapted to monitor and analyze presence of the 
ring signal detected by said telephone interface means, and said 
microcontroller means are adapted to monitor and analyze an output of said 
differential amplifier means. 
Still in another embodiment, said microcontroller means when placing a call 
in a default mode are adapted to provide the pulse dialling mode, and said 
microcontroller means are adapted to disable said pulse dialling means and 
to enable said DTMF generator means after the presence of the ring back 
signal is detected by said differential amplifier means and after said 
ring back signal was analyzed and confirmed by said microcontroller means. 
The handset means is connected to said telephone interface means and said 
keypad means is connected to said microcontroller means, and in said pulse 
dialling mode a keypad entries will be transferred into a pulse signals, 
and in said DTMF dialling mode the keypad entries will be transferred into 
a DTMF signals. 
Also, the present invention includes a telecommunication method enabling a 
user to get access to an automated call processing system, such as voice 
mail or the like, which access is strictly limited to a DTMF dialling mode 
from central office restricted to processing calls in a pulse dialling 
mode, said method comprising the following steps: 
constantly monitoring a telephone line; 
analyzing a tone progress signal on said telephone line; 
switching in a correct instant between the pulse dialling mode and the DTMF 
dialling mode to facilitate the access to said automated call processing. 
The monitoring of said telephone line is provided to detect a ring signal 
indicating a receiving call mode, and the monitoring of said telephone 
line is provided to detect a ring back signal indicating a placing call 
mode. In said receiving call mode the DTMF dialling mode is activated to 
allow further DTMF entries, and in placing call mode said pulse dialling 
mode is firstly activated in the moment when the user started to initiate 
his call via said central office operating on the pulse dialling mode. 
In still another embodiment, said placing call mode the DTMF dialling mode 
is activated after the detection of the ring back signal was analyzed and 
confirmed to enable the user to get access to said automated call 
processing, and in receiving mode the DTMF dialling mode is activated. In 
said placing call mode the DTMF dialling mode is disactivated until the 
confirmation of the detection of said ring back signal, wherein said 
confirmation is indicating that the call has been processed by the central 
office, and in receiving call mode the ring signal is detected by a 
telephone interface means. 
In yet another embodiment, the monitoring and analyzing of said telephone 
line is provided by a control means, and the detection of said ring back 
signal in said placing call mode is provided by differential amplifier 
means incorporated within said control means. Said control means are 
providing automatic switching between said pulse dialling mode and said 
DTMF dialling mode in response on analysis of the tone progress signal of 
said telephone line, wherein said tone progress signal is the ring back 
signal processed by said central office. 
In another embodiment of the present invention, said DTMF dialling mode is 
provided by means of a DTMF generator means incorporated within said 
telephone interface means, and said pulse dialling mode is provided by a 
pulse dialling means incorporated within said control means. Said 
telephone interface means are communicating with said control means by 
means of a set of predetermined commands providing successful operation of 
all steps of said method, and dialling entries are provided by a keypad 
means connected to said control means and wherein in said pulse dialling 
mode said entries will be transferred into the pulse dialling signals and 
in said DTMF dialling mode said entries will be transferred into the DTMF 
dialling signals.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The main principle of the present system is based on analyzing the tone 
progress signals of the telephone line and based on that analysis choosing 
the correct instant of switching between pulse dialling mode and tone or 
DTMF dialling mode. While in placing a call mode the ring back signal is 
analyzed and in receiving call mode the ringing signal is analyzed. The 
present invention is equipped with special circuitry that constantly 
monitor the telephone line. When the telephone receives a call the ring 
signal is detected by its internal circuitry and upon an "off hook" 
condition the dialling mode is set to tone or DTMF. An "off hook" 
condition indicates the user of the telephone has answered the call. 
As it shown on FIG. 1, in a placing call mode there is no ring signal on 
the telephone line. An "off hook" condition has been detected by the 
circuitry of the telephone, which is an indication that the user will 
place a call. In this case the initiating dialling mode will be the pulse 
dialling since CO can process only pulse dialling. Once dialling has been 
terminated, the telephone starts to monitor the telephone line waiting for 
the ring back signal to be present. Upon the detection of the ring back 
signal the dialling mode is switched into DTMF which permits the user to 
get access to the application that require so. In this case, the presence 
of the ring back signal is an indication that the call has been processed 
by the CO and the telephone is ringing at the called party side. 
Referring now to FIG. 2 a block diagram of the present invention is shown. 
It comprises a telephone line interface means connected to telephone line 
having Tip and Ring identifications. The system also includes a control 
means connected to said telephone line and to said telephone interface 
means. Handset and keypad means are connected to said telephone interface 
means and said control means respectively. The telephone line interface 
means further comprises microprocessor means or integrated circuit means 
and a pulse dialling means or circuit. Preferably, but not necessary said 
microprocessor comprises TEA 7090 single chip device from SGS-Thomson 
which integrates the basic functions of a telephone set on one chip, such 
as: 
The speech network 
The DTMF or tone generator 
The finger 
Microcontroller interface 
The speech network includes a transmitter and receiver channels, to which a 
handset receiver and handset microphone can be connected. 
The DTMF generator is an "on-board" generator. Based on codes received from 
the microcontroller means the correct DTMF signal will be placed on the 
telephone line. In this case the microcontroller means supplies the clock 
of the DTMF generator. 
The ringer can generate up to 8 different tones and the volume of the 
finger can be controlled through the microcontroller means. 
The microcontroller interface of said microprocessor includes the following 
output pins (see FIG. 3) by which it communicates with the microcontroller 
means: 
Power supply (VRMC)--this output comprises the 3.5 V regulated voltage 
supply for the microcontroller means. 
Ring Indicator Output (RI)--this signal indicates the presence of a ring 
signal on the telephone line. The control circuitry or the microcontroller 
constantly monitors this output pin of the microprocessor. 
Power On (PON)--as soon as power supply (VRMC) exceeds 3.15 V, this pin 
becomes active and indicates that the line current is present. Combined 
with the reset signal the control circuitry will validate the "off hook" 
condition. 
Reset--this output becomes high on the first positive edge of PON (power 
on) and stays high as long as power supply (VRMC) is greater than 3.15 V. 
Mask (MSK)--is an input pin which should be low during pulse dialling mode. 
DTMF Clock (CLK)--this is the clock for the DTMF generator which is 
supplied by the microcontroller. 
Serial Byte Interface (DATA and DCL)--are input pins which carry the 
necessary codes to control the microprocessor, those codes are: 
The DTMF and ring frequency codes; 
The mode codes (dialling, speech, mute, ring); 
The configuration codes (mask/no mask, receive gain, ring levels, reset 
codes). 
Those codes are provided by the microcontroller means of said control 
means. Referring now to FIG. 4 a pulse dialling means or circuit is shown. 
It comprises a two-transistor network, which is used to interrupt the loop 
current and to perform a pulse dialling mode. The transistor network is 
controlled by one of the output pins of the microprocessor means which 
sends the correct number of the make/break pulses based on the pressed 
keypad key. 
The control means of the present invention performs the following 
functions; 
Interfacing with the keypad means and decoding the pressed keys or entries; 
Performing the pulse dialling; 
Constantly monitoring the telephone line and the RI, PON and RESET pins of 
the microprocessor means and switching from pulse dialling when there is a 
ring back signal or ring signal on the telephone line; 
Interfacing with the microprocessor and performing control functions (DATA 
and DCL). 
The control means or circuitry is composed of a micro controller means and 
a differential amplifier means. As it shown on FIG. 6 the inputs of 
differential amplifier is connected to the Tip and Ring of the telephone 
line and its output is connected to the A/D (Analog to Digital) converter 
of the microcontroller. This output pin is constantly monitored and 
analyzed for the ring back signal, which is very important feature of the 
present invention. 
Preferably, but not necessary the control means or the microcontroller 
means comprises the ST6294 from SGS-Thomson and most of the above 
mentioned operations are performed within the microcontroller by means of 
predetermined set of commands. 
As shown on FIG. 5, a handset means is connected to the receiving and 
transmitting channel of the speech network of the microprocessor means. 
A keypad means is connected to I/O (input/output) pins of the 
microcontroller means. The microcontroller scans the keypad entries, which 
the user uses to enter numbers. In pulse dialling mode keypad entries will 
be transferred into dial pulse, and in DTMF dialling mode keypad entries 
will be transferred into DTMF signals. 
Keypad is also used to perform last number redial and memory dialling. 
The present invention operates in two modes which will be discussed below: 
Receiving Call Mode 
The microcontroller means constantly monitors RI, PON and RESET signals of 
the microprocessor. When the phone is ringing RI signal will be active 
indicating the presence of a ring signal on the telephone line. When the 
user answers the phone (Off hook condition), the PON and RESET signals of 
said microprocessor become active indicating an "off hook" condition to 
the micro controller. Those active RI signals followed by active PON and 
RESET signals is a valid condition to changing the dialling mode to DTMF. 
In this case the pulse dialling circuit is disabled and the DTMF generator 
of said microprocessor means is enabled. All keypad entries scanned by the 
microcontroller are decoded and sent to the microprocessor by means of the 
DATA and DCL signals, so that the microprocessor places the corresponding 
DTMF signals on the telephone line. During DTMF or tone dialling mode, 
keypad entries will generate DTMF tones. For example, if the user presses 
"1", the telephone will place the equivalent DTMF signal on the telephone 
line which is the combination of two frequencies 697 Hz and 1209 Hz. 
Placing Call Mode 
When the user lifts the handset of the phone to place a call, the PON and 
RESET signals of the microprocessor means become active indicating an "off 
hook" condition. The microcontroller constantly monitor the RI, PON and 
the RESET pins of the microprocessor. An active PON and RESET signals 
without the presence of an active RI signal is an indication that the user 
will place a call. In this case the telephone has to be in pulse dialling 
mode, therefore the microcontroller disables the DTMF generator of said 
microprocessor and activates the pulse dialling means or circuit. In the 
pulse dialling mode the telephone will generate dial pulses for each 
pressed keybutton. The pulse dialling is achieved through one of the 
output pins of the microcontroller which drives the line break transistor 
in the pulse dialling circuit of FIG. 4. The number of pulses depends on 
the sequence of the depressed keys. When the user has finished dialling 
the number, the microcontroller starts monitoring and analyzing the output 
of the differential amplifier means of FIG. 6. The output signal of said 
amplifier means is an analog signal, and before performing any analysis, 
the microcontroller will first convert this signal into a digital format 
by means of using A/D converter incorporated on said microcontroller. 
After A/D conversion, filtering and zero crossing analysis are performed 
on said signal and as result of this analysis the presence offing back 
signal is finally confirmed. Upon the detection and confirmation of the 
ring back signal the microcontroller stops monitoring the output of the 
differential amplifier means, disables or switches automatically without 
human intervention the pulse dialling circuit and enables the DTMF 
generator of said microprocessor. This operation will change the dialling 
mode of the telephone from pulse into DTMF. During DTMF or tone dialling, 
keypad entries will generate DTMF tones. For example, if the user presses 
"1", the telephone will place equivalent DTMF signal on the telephone line 
which is the combination of two frequencies 697 Hz and 1209 Hz. The 
telephone will stay in tone or DTMF dialling mode as long as the user 
stays in "off hook" condition. Once the phone goes "on hook", the 
microcontroller will immediately reset the whole processes of detection, 
and analysis will start from the beginning. FIGS. 7 and 8 illustrate the 
flow-chart of the commands operating steps of the method according to the 
present invention the details of which are explained below: 
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FLOW CHART DETAILS 
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Bloc TELEPHONE SET Power On, the program 
starts here 
Bloc SET TIMER A Counter is initialized. This 
will determine the keypad 
scanning interval. 
Question RI On? Is the Ring Indicator On? Is 
the telephone ringing? If yes, 
it means we are receiving a 
call. 
Question RESET On? Is the Reset Indicator On? Is 
the telephone handset up? If 
we were receiving a call, it 
means the call was 
answered. 
Bloc SWITCH TO DTMF 
Change the Dialling Mode 
from Pulse to Tone (Touch 
Tone). 
Bloc SCAN KEYPAD Scan the keypad to check if 
any number was pressed. 
Question DIGIT? Was a digit pressed? 
Bloc DIAL DIGIT + Dial the digit pressed by user 
SET TIMER and reinitialise the timer. 
Bloc TIMER When we are placing a call, 
this bloc is started any time 
we complete one period of 
timer, what ever is the state 
of the system. 
Question TIMER = 0? 
Is the Timer Counter = 0? 
Is the period of time expired? 
Bloc ANALYZE LINE SIGNAL 
Take a sample of the line 
signal and analyze it. 
Question RING BACK On? 
Is the ring back signal 
on the line? 
Bloc RESET TIMER Reinitialise timer counter. 
Bloc RETURN Since this part of the 
program (TIMER) is started 
at the end of a timer period 
no matter what is the state 
of the system, this bloc goes 
back to the point where the 
system was at the end of 
the period. 
______________________________________ 
Thus the present invention allows the user to get access to any automated 
call processing system including, but not limiting, to automated 
attendant, voice mail, telebanking, voice response, digital paging etc., 
access to which are strictly limited to callers equipped with a DTMF 
telephone and central office services based on DTMF. 
The telephone according to the present invention can also be combined with 
many other features, such as speaker-phone, speed dialling or last number 
redial or the like, without any interferance with the proper functionality 
of the telephone. 
It will be obvious to those skilled in the art that numerous modifications 
of the present invention may be made without departing from the spirit of 
the present invention which shall be limited only by the scope of the 
claims appended hereto.