Tone-type recognition method

• US 5,063,593 A
• Filed: 08/23/1989
• Issued: 11/05/1991
• Est. Priority Date: 08/23/1989
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kwon, Oh-Seol
• Primary Examiner(s): Ng, Jin F.
• Assistant Examiner(s): Augustus, Jhancy
• Application Number:
  US07/397,254
• Time in Patent Office: 804 Days
• Field of Search: 379/372, 379/377, 379/381, 379/382, 379/386
• US Class Current: 379/386
• CPC Class Codes: H04M 1/82 Line monitoring circuits for call progress or status discrimination for detecting caller identity H04M1/573

Abstract

There is disclosed a tone type recognition method capable of recognizing a call progress state of a central office line switching system by using a tone detector. The method enables the system to correctly recognize the type of call progress tone, regardless of its frequency, by conducting periodic detection of characteristics of cadence classified by tone-type.

Claims

1. A tone-type recognition method in a switching system, said method comprising the steps of:

reading an initial tone type from a tone detector upon receipt of a request for a tone-read operation and specifying a "tone-off" wait state if the tone type is determined to be in an "on" state upon receipt of the request or a "tone-on" wait state if the tone type is determined to be in an "off" state upon receipt of the request; and

reading the tone state from the tone detector periodically based on the wait state specified in said step of specifying, counting a number of "tone-on" states if the "tone-on" wait state is the specified state or counting a number of "tone-off" wait states if the "tone-off" wait state is the specified state, and identifying tone-type according to said count.

2. A method as claimed in claim 1, wherein said step of periodically reading the tone state is performed in intervals of about one hundred milliseconds.

3. A method as claimed in claim 1, further comprised of identifying said tone-type as a dial tone when said count of "1" has a value greater than ten.

4. A method as claimed in claim 1, further comprised of identifying said tone-type as a silence tone when said count of "0" has a value greater than ten.

5. A method as claimed in claim 1, further comprised of identifying said tone-type as a busy tone when said count of "0" or said count of "1" has a value equal to ten.

6. A method as claimed in claim 1, further comprised of identifying said tone-type as a ring back tone when said count of "0" or said count of "1" has a value equal to five.

7. A tone type recognition system for a central office line switching system, comprising:

a relay for connecting said recognition system to said central office line switching system;

a relay driver for driving said relay;

a hybrid interface receiving first signals from said relay for sending to a subscriber based on operation of the relay;

a tone detector for checking tones in signals received from said hybrid interface, for producing a second signal of high logic level if a tone is detected, and for producing a third signal of low logic level if no tone is detected;

a line interface for delivering said second or third signals from said tone detector to a microprocessor; and

a codec for converting analog voice signals received from said hybrid interface into digital signals.

8. The tone type recognition system of claim 7, further comprised of said line interface controlling operation of said relay driver.

9. The tone type recognition system of claim 7, further comprised of:

said relay driver driving said relay between ON and OFF states;

said hybrid interface sending said first signals to the subscriber in accordance with said ON and OFF states of said relay driver; and

said line interface beomg coupled to said relay driver.

10. The tone type recognition system of claim 7, further comprised of:

said relay applying a plurality of tones representing service progress states to said hybrid interface section;

said relay driver driving said relay between ON and OFF states;

said hybrid interface sending said first signals to the subscriber in accordance with said ON and OFF states of said relay driver; and

said line interface being coupled to apply signals to said relay driver.

11. A non-periodic tone-type recognition method for determining the existence of a tone in a switching system, said method comprising the steps of:

setting a tone-read enable flag for a port;

checking if a tone is present at said port;

setting a "tone-off-wait" state if no tone is present at said port; and

setting a "tone-on-wait" state if a tone is present at said port.

12. A periodic tone-type recognition method in a switching system, said method comprising the steps of:

checking if a tone-read enable flag is set at a port;

stopping the search if the tone-read enable flag is not set for said port;

checking for the presence of a tone at said port if the tone-read enable flag is set;

performing a "tone-off-wait" state function if a tone is present at said port; and

performing a "tone-on-wait" state function if no tone is present at said port.

13. A method as claimed in claim 12, wherein said "tone-off-wait" function comprises the steps of:

checking for the presence of a "tone-off-wait" state;

checking for the presence of a "tone-on-wait" state if no "tone-off-wait" state is present;

setting a tone-on increase state during the presence of a "tone-on-wait" state;

checking if a tone-off-increase state is set when no "tone-on-wait" state is present;

counting a number of "1" upon detection of a tone-on-increase state or tone-off-increase state;

clearing the tone-on-wait state;

checking if the count of "1" is greater than 10;

determining the tone-type to be a dial tone if the count of the number of "1" is greater than 10;

determining the tone-type by a number of "0" counted if the tone-on-increase state is not set; and

clearing the set of the tone-read-enable flag.

14. A method as claimed in claim 12, wherein said "tone-on-wait" function comprises the steps of:

checking for the presence of a "tone-on-wait" state;

checking for the presence of a "tone-off-wait" state if no "tone-on-wait" state is set;

setting a "tone-off-increase" state if a "tone-off-wait" state is present;

checking for the presence of a "tone-off-increase" state if no "tone-off-wait" state is set;

counting a number of "0" upon detection of a "tone-increase" state;

clearing the "tone-off-wait" state;

checking if the count of "0" is greater than 10;

determining the tone-type to be a silence tone if the count of the number of "0" is greater than 10;

determining the tone-type by a number of "1" counted if the "tone-on-increase" state is not set; and

clearing the tone-read-enable flag.