FIELD OF THE INVENTION
The invention relates to the field of telecommunication, more specifically, the invention relates to providing audio file service to telecommunication users.
DEFINITIONS
Communication Network Communication network is a network for establishing communication. Communication includes, but Is not limited to, transferring information and data such as voice, audio, video, graphics and the like. Examples of communication network includes, but is not limited to, internet, intranets. Wide Area Networks (WANs), Local Area Networks (LANs), transducer links such as those using Modulator-Demodulators (modems), telecommunication infrastructure which includes Public Switched Telephone Network (PSTN), Global System for Mobile Communications (GSM), and CDMA network.
Communication device: A communication device is a device used to establish communication through the communication network. Different communication networks may use different communication devices. For example, communication devices to establish communication in a telecommunication Infrastructure include, but are not limited to, voice phone, cordless phone, landline phone and mobile phone.
User A person using the communication device to communicate with another user through the communication network.
Caller: A user initiating a call to another user using a communication device is referred to as a caller. For example, a user using a landline phone, in the telecommunication infrastructure, to call another user is a caller.
Callee: A user receiving a call from the caller using a communication device is referred to as a Callee. For example, in a telecommunication Infrastructure, the callee may receive a call using a mobile phone.
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Mobile Switching Center (MSC): An IVISC enables communication in a GSM network. MSC is responsible for handling voice calls and other services such as conference calls and FAX. Handling voice call includes setting and releasing the call, handling mobility and handover requirements during a call. Handover requirements comprise switching base stations when a user shifts from range of one base station to another during a call. The base stations are responsible for transmitting and receiving call signals.
Home Location Register (HLR): HLR is a database comprising of subscription status, user information, user account ^details and the like. Subscription status includes information on whether a callee is subscribed to an audio file service. User information includes address, mobile number and the like. Account details include account status, balance status of user and the like.
Value Added Service (VAS): The additional services provided by communication service provider other than standard voice calls and fax transmissions. These additional services are generally provided to attract more customers and thus increasing revenue. Examples of VAS include Audio file (audio file) service, ringtones, call forwarding and the like.
RBT Service: The RBT service enables a user to select an RBT to be played to any caller calling the user. Typically, the user registers with an RBT system to avail her RBT service. A user registered with the RBT system for RBT service is referred to as an RBT subscriber.
Audio file: An audio file comprises data audio data. An audio file may be a song, a tune, an advertisement, voice messages, ringtones, ring back tones and the like.
Ring back tone (RBT): An audible sound that is played to a caller when the caller is waiting for the callee to pick up the call. RBT may be any musical sound, song, tune of a song, advertisements, personalized messages and the like.
Interactive Voice Response (IVR): IVR is a technology that enables voice interaction between a computer system and a user on telephone. The computer
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system is able to detect voice signals and respond to the user according to a prerecorded message stored with the computer system.
Outbound Dialer: Outbound dialer is a system used to make calls to users and accepts inputs from the users. The outbound dialer selects users to call, from a predefined list of users' telephone numbers. An outbound dialer is capable to detect and skip a call with a busy signal, or end of call connection or an answering machine at other end of the call. Outbound dialers are mostly used for telemarketing.
RBT system: RBT system is responsible for playing RBT. ROT system also receives requests for certain services from the caller during playing of the RBT. The services include, but are not limited to, registering a user for the RBT service, providing RBT, bookmarking RBT and the like to a user who has registered to the RBT service. The requests may be sent through various means, for example, voice, pressing DTMF keys and the like.
Content Provider: An entity that provides audio files to a request processing system.
Dual Tone Multiple Frequency (DTMF): Dual Tone Multi-Frequency, or DTMF signals are used for instructing a telecommunication network of the telephone number to be dialed, or to issue certain requests to switching systems or related telephony equipment. A DTMF signal is generated when a key on a mobile device is pressed. Each key on the mobile device has a unique DTMF signal associated with the key. The DTMF signal comprises two frequencies making a frequency pair, meant for identification of the key pressed on the mobile device. For example, '*' key on the mobile device has frequency pair of 941 Hz and 1209 Hz forming a DTMF signal corresponding to '" key. A DTMF signal may be used io send requests to the Request processing system during playing of an audio file.
Frequency Spectrum: Frequency spectrum of an audio file comprises the frequencies present in the audio file.
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Modified audio file: Modified audio file is produced from an audio file by modifying a set of frequencies present in the audio file. The set of frequencies may include the frequencies corresponding to DTMF signals in the audio file. The set of frequencies may also be the entire frequency spectrum of the audio file. Modification may include removing or attenuating the set of frequencies present in the audio file. For example, suppose an audio file having DTMF signal corresponding to "" key. After processing the audio file, the modified audio file will either not have 941 Hz or 1209 Hz frequencies in its frequency spectrum or the amplitude of the DTMF signal will be below threshold amplitude. A modified audio file may also have a shifting of its frequency spectrum to a higher or lower level of frequencies such that frequencies corresponding to a DTMF signal get shifted to new frequencies. For example, '*' key DTMF frequencies may get shifter by 200 Hz to 1141 Hz and 1409 Hz. In case, the DTMF signals are not present in an audio file, then the modified audio file is same as corresponding audio file.
Frequency Filter; A device to filter specific frequencies or a frequency band in an audio file. Filtering specific frequencies may comprise removing the frequencies or attenuating the frequencies. Examples of frequency filter include, but are not limited to, a band stop filter and a fully parametric equalizer.
BACKGROUND
Value added services (VAS) are gaining popularity in the telecommunication domain. Typical VAS includes services like RBT, ringtones, call forwarding and the like. A very popular service is ring back tone {RBT) service. The RBT service enables replacement of a conventional 'tring tring' lone heard by a caller, with an RBT, An RBT may be some musical tune, song, advertisements, personal message and the like.
The RBT is played by an RBT system. Typically, RBT system plays the RBT to a caller while the caller is waiting for the callee to pick up the call. Prior art teaches methods wherein caller may send requests to the RBT system during playing of the RBT. Such requests may be sent by the caller through pressing of
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DTMF keys. The pressing of a DTMF key result in a DTMF signal being sent to the RBT system. The DTMF signal includes a pair of frequencies. For example, pressing of '*' key results in a DTMF signal with frequencies 941 Hz and 1209 Hz. The user may press multiple DTMF keys. For example, pressing of '1' and '2' keys will result in a DTMF signal with frequencies 697 Hz, 1209 Hz and 697 Hz, 1336 Hz.
Examples of prior art teaching sending of such requests include Korean patent KR4013330A titled 'Method for setting ring-back tone alternative sound of caller to ring-back tone alternative sound of receiver in mobile communication system using ring-back tone alternative sounds' and US Publication no. US20070003047A1 titled 'Ringback tone bookmark request by calling party'. KR4013330A enables the caller to send a request for copying the ring back tone of callee through pressing of DTMF keys. US20070003047A1 discusses a method which enables a caller to send a request to bookmark an audio file.
Such requests are received by the RBT system. RBT service providers configure the RBT system so that the RBT system may receive such request. Configuring an RBT system results in the RBT system 'listening' to such requests. Such a configured RBT system is thus able to recognize the pressing of DTMF keys and takes pre-specified actions such as copying the RBT of callee, bookmarking the RBT etc.
However, requests are sometimes generated and sent to the RBT system, during playing of RBT, even though the caller has not pressed a DTMF key. Such requests are hereinafter referred to as false requests. 'One of the causes of generation of false request is echo in the telecommunication system.
Echo is reflection of a wave due to some discontinuity in propagation medium. During playing of the RBT, echo may result in reflection of RBT signal back to the RBT system. The reflected RBT has same frequency spectrum as the RBT. If the RBT has DTMF signals in its frequency set, then reflected RBT also has the same DTMF signals in its frequency set. For example, the reflected RBT signal may have frequencies corresponding to the DTMF key '*', i.e. 941 Hz and
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12D9 Hz frequencies, in its frequency set. When such a reflected RBT signal will reaches the RBT system, the RBT system will detect the presence of frequencies corresponding to the DTMF key '*'. On detection, the RBT system will interpret the presence of such frequencies as a 'request' by the caller through pressing of DTMF key '*'. The RBT system will then take pre-specified action in response to the 'request'. Such pre-specified action could be making the RBT of callee as RBT of caller, as taught in KR4013330A. Thus the caller has to pay for the change in RBT even though there was no request from her.
Such an undesirable change in RBT not only results in incurring of unnecessary charges by the caller but also annoys the caller. It may further cause caller dissatisfaction and the caller may unsubscribe from the RBT service. A situation like this also damages the market image of the RBT service provider. A large number of such accumulated requests may also result in wastage of useful data storage space in the RBT system.
A solution to the above problem Is to not configure the RBT system for receiving such requests. However, receiving requests from a caller during playing of RBT is a popular service and disabling such a sen/ice would result in RBT service providers losing a lot of money.
Examples of other systems where such problem may occur are, without limitation, an IVR system and an Outbound dialer. Systems where such problems may arise are referred to as request processing systems. Any ring back tone, ring tone, song, news etc. played to caller is referred to as an audio file.
Therefore there is need of a system to prevent generation of false request to the request processing system while ensuring that request processing system may receive genuine requests from callers during playing of audio file.
SUMMARY OF THE INVENTION
A method for preventing generation of a false request to a request processing system is disclosed. The method comprises analyzing the presence of at least one DTMF signal in an audio file, modifying a set of frequencies
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present in the audio file based on the analysis and playing the modified audio file upon receiving notification. The modification may be done before or after receiving the notification. The generation of false request during playing of modified audio file Is prevented due to non-recognition of DTMF signals in the reflected modified audio file by the request processing system.
A system for preventing generation of a false request to a request processing system Is disclosed. The false request Is being generated during playing of an audio file, in response to presence of at least one DTMF signal in the audio file. The system comprises a graphical User Interface or GUI, frequency processing unit and a tone player. The GUI generates commands for modifying the audio file. The frequency processing unit is responsible to modify the audio file according to the commands received from the GUI. The frequency processing unit comprises a frequency filter, a pitch shifter and an encoder. The frequency fitter is configured to filter at least one frequency from the frequency pair corresponding to the DTMF signal in the audio file to generate to modified audio file. The pitch shifter is configured to shift the frequencies of the audio file to generate a modified audio file. The encoder creates a clip associated with the modified audio file vi/hich comprises information for playing the audio file and receiving request. The tone player is configured to play the modified audio file.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 Is a schematic representing the environment of the invention In accordance with an embodiment of the invention.
FIG. 2 is a flowchart describing a first method to prevent generation of a false request to a request processing system, in accordance with an embodiment of the invention.
FIG. 3 is a flowchart describing a second method to prevent generation of a false request to a request processing system, in accordance with an embodiment of the invention.
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FIG. 4 is a schematic representing a request processing system in accordance with an embodiment of the invention.
FIG. 5 is a schematic representing the application server in accordance with an embodiment of the invention.
FIG. 6A and FIG. 6B are flowcharts describing static modification of an audio file, in accordance with an embodiment of the invention.
FIG. 7 is a flowchart describing runtime modification of an audio file, in accordance with an embodiment of the invention.
DETAILED DESCRIPTION
A method and system for preventing generation of false request to a request processing system is disclosed. The false request is generated during playing of an audio file to a caller due to presence of DTMF signals in the audio file. The audio file without limitation may be a ring back tone, a personalized message, a song, a ringtone, a tune, an advertisement, a voice message and the like.
In the following description numerous specific details are set forth to provide a more thorough description of the present invention. It would be apparent, however, to one skilled in the art, that this invention can be carried out without these specifications.
FIG. 1 is a schematic representing the environment of the invention in accordance with an embodiment of the invention. The environment comprises telecommunication infrastructure 102. caller 104 and callee 106. Telecommunication infrastructure 102 connects caller 104 to callee 106. Caller 104 can make a call to callee 106 using telecommunication infrastructure 102. Telecommunication infrastructure 102 comprises MSC 108, HLR 110 and request processing system 112. According to an embodiment, request processing system 112 plays a ring back tone to caller 104. According to another embodiment caller 104 may make a call directly to the request processing system 112. Examples of
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^ request processing system 112 include, but are not limited to, an RBT system, an IVR system and an Outbound Dialer.
According to an embodiment, MSC 108, after receiving call request from caller 104, establishes call connection between caller 104 and callee 106. MSC 108 also checks for the subscription status of callee 106 after receiving the call request. HLR 110 stores subscription status of callee 106. Subscription status includes information on whether callee 106 is subscribed to an RBT service. In case catiee 106 is subscribed to RBT service, MSC 108 forwards the call to request processing system 112. Thus a call connection is established between caller 104 and request processing system 112 and also between caller 104 and callee 106. Request processing system 112 plays an RBT of callee 106 to caller 104 while caller 104 is waiting for callee 106 to respond to the call. During playing of the RBT, request processing system 112 may receive requests from caller 104. In one embodiment, request may be sent by caller 104 through DTMF keys.
After callee 106 has responded to the call, call connection between caller 104 and request processing system 112 ends and conversation between ca\ler 104 and callee 106 begins.
According to another embodiment of the invention, caller 104 may directly call request processing system 112 to listen to an audio file. The audio file may be a song, ringtone, and the like. In such a scenario also, request processing system 112 may receive requests from caller 104 during playing of the audio file. Such request may include a DTMF key response to make the audio file as RBT or ringtone of caller 104.
It will be apparent to a person skilled in the art that selecting an audio file to be played to caller 104 or the content of audio file is not a limitation of this invention.
Request processing system 112 is explained in detail In conjunction with FIG. 4.
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Fig. 2 is a flowchart describing a method to prevent generation of a false request to request processing system 112, in accordance with an embodiment of the invention. In ttie embodiment, audio files are processed and stored in database. These audio files are then played by request processing system 112 on receiving a notification.
At step 202, an audio file is analyzed for the presence of DTMF signal. The analysis comprises detecting presence of at least one DTMF signal in the audio file and determining the prominence of the DTMF signal in the audio file. A DTMF signal is considered very prominent In the audio file if the frequencies corresponding to the DTMF signal are present throughout the audio file. In such a scenario, removing frequencies corresponding to such a DTMF signal will affect the quality of the audio file. Also an audio file may comprise frequencies of only DTMF signals. Thus removing a DTMF signal from such an audio file will greatly affect the quality of the audio file. On the other hand, if the frequencies corresponding to a DTMF signal appear at a few places in the audio file, then the prominence of that DTMF signal is low in the audio file. Removing the frequencies corresponding to such a DTMF signal is not expected to deteriorate the quality of the audio file.
At step 204, based on the analysis of the audio file, a set of frequencies of the audio file is modified from at least one portion of the audio file. The step of modification comprises either filtering the frequencies corresponding to DTMF signals present in the audio file or shifting entire frequency spectrum of the audio file. The process of modifying the audio file is described in detail in conjunction with FIG. 6Aand FIG. 6B.
The modified audio file is stored in a database. At step 206, on receiving a notification, the modified audio file is played by request processing system 112.
When the modified audio file is played, any reflection of the modified audio file will not cause generation of false request since request processing system 112 is not able to recognize DTMF signals in the modified audio file.
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FIG. 3 is a flowchart describing another embodiment in which generation of a false request to a request processing system is prevented. In the embodiment, unprocessed audio files are stored in a database. When a notification to play an audio file is received by request processing system 112, the unprocessed audio files undergo modifications at runtime, before being played.
The notification is received by request processing system 112 at step 302. Receiving of a notification is explained in conjunction with FiG, 4.
At step 304, audio file information of the audio file is retrieved. The audio file information comprises information about presence of DTMF signals in the audio file. The audio file information further comprises details for modification of the audio fits.
At step 306, based on the audio file information, a set of frequencies in the audio file is modified. The set of frequencies are modified at one or more portions of the audio file. The step of modification comprises either filtering the frequencies corresponding to DTMF signals present in the audio fiie or shifting entire fi-equency spectrum of the audio file. The process of modifying the audio file is described in detail in conjunction with FIG. 7.
At step 308. the modified audio file is played by request processing system 112.
When the modified audio file is played, any reflection of the modified audio le w,l, not cause generation of false request .ince request processing system 112 IS not able to recognize DTMF signals in the modified audio file.
FIG. 4 is a schematic representing request processing system 112 in accordance With an embodiment of the invention,

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Dialer and the like. Request processing system 112 receives call information from MSC 108 when MSC 108 establishes call connection between caller 104 and request processing system 112. The call information includes, but is not limited to, phone number of caller 104 and phone number of cailee 106. Further, the call information may contain request for request processing system 112, According to an embodiment the establishment of call connection between caller 104 and request processing system 112 is a notification to request processing system 112 for playing the audio file. For example, when caller 104 calls cailee 106 wherein caliee 106 is RBT subscribed, then request processing system 112, which is RBT system in this case, receives notification to play RBT of caliee 106 as call gets connected.
According to another embodiment, the notification to play the audio file may be received when caller 104 sends a request. The request may be in form of voice signal or a DTMF signal. For example, when caller 104 interacts with IVR system, caller 104 is provided option to choose a hngtone to be played from a list of ringtones. Caller 104 may choose the ringtone through pressing of a DTMF key. For example, caller 104 may be given an option by the IVR system to choose a ringtone from a list of 5 ringtones. To choose ringtone 1 key '1' is pressed, to choose ringtone 2 key '2' is pressed and so on.
Further, request processing system 112 comprises one or more signaling canj 402, one or more media card 404 and an application server 406.
Signaling caret 402 transmits specific information regarding call connection from MSC 108 to request processing system 112. For Example signaling card 402 transmits information regarding establishment of call, termination of call etc. Further call information is forwarded to application server 406 by signaling card 402. The signals from MSC 108 are transmitted using standard protocols such as SS7. Signaling card 402 includes a software component for signal handling. The software component may be programmed in programming languages such as C, C++ and the like. An example of signaling card 402 is NMS TX-4000 card.
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A media signal to and from request processing system 112'passes through media card 404. Media signal includes DTMF signals, RBT, voice messages and the like. A request to request processing system 112 in the form of DTMF signals passes through media card 404. Media card 404 includes a software component for handling media signals. The software component may be programmed In programming languages such as C, C++ and the like. An example of media card 404isNMSAG-4040card.
Application server 406 contains applications written in programming language such as C/C++, Java and the like. Application server 406 is responsible for playing audio file and for receiving requests from caller 104 during playing of the audio file. Application server 406 has been explained in detail in conjunction with FIG. 5.
FIG. 5 is a schematic representing application server 406 in accordance with an embodiment of the invention. Application server 406 comprises a plurality of applications 502, a tone player 504, a database 506, a GUI 508 and a frequency processing unit 510.
Application 502 is responsible for receiving call information and notifications to request processing system 112, from signaling card 402. Further, application 502 provides tone player 504 with audio file information stored in database 506.
According to an embodiment, the audio file information of an audio file comprises audio file id of the audio file and the listening zone information of the audio file.
According to another embodiment, the audio file information of the audio file comprises audio file id, listening zone information for the audio file, details about prominence of DTMF signals in the audio file and modification details for modification of the audio file. Listening zone information defines the duration for which tone player 504 listens or accepts requests from caller 104, during playing of the audio file. For example, an audio file may be played for 10 (ten) seconds. The listening zone for that audio file may be, for example, from 3-7 seconds
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during playing. Thus, tone player 504 will not recognize any request during 1-2 seconds and 8-10 seconds duration of playing of the audio file. Listening zone information further comprises information regarding the requests which tone player 504 should listen to in the listening zone. In the above mentioned example, listening zone information includes, for example, information that tone player should listen to frequencies corresponding to '1' DTMF key in the listening zone of 3-7 seconds of playing of the audio file. Listening zone is different for different audio files. Further, listening zone information for an audio file which is played due to instructions from an application may be different when the audio file is played based on instructions from a second application. For example, when an audio file is played as ring back tone, the listening zone information could be '0-5 seconds' and 'listen to frequency corresponding to '#' DTMF key'. When the same audio file is played as a song in an IVR system, the listening zone information could be '2-5 seconds' and 'listen to frequencies corresponding to '1' DTMF key'. Further, the listening zone information may be different when the audio file is played to one caller from when the audio file is played to a different caller.
Modification details of the audio file in the audio file information will comprise instructions for modifying portion of that frequency spectrum of the audio file which falls under the listening zone of tone player 504 for the audio file. The modification details, example, includes, information regarding filtering of frequencies corresponding to '1' DTMF key from the listening zone of the audio file, i.e. 3-7 seconds.
For playing of an RBT, application 502 is an RBT application which receives notification for playing of ring back tone. Application 502 may be an IVR application when caller 104 is directly calling the request processing system 112.
Tone player 504 receives call information and audio file information from application 502. Tone player 504 comprises a control unit 512 which analyses the audio file information. Based on the analysis tone player 504 retrieves the audio file from database 506 and plays it. The audio file played by tone player 504 may
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be an RBT set to callee 106. The audio file may further be a song from a list of latest songs or a ringtone stored in database 506. It will be apparent to any person skilled in the art that selecting an audio file to be played to caller 104 is not a limitation of the invention.
Tone player 504 plays an audio file till the time MSC 108 terminates call connection between caller 104 and request processing system 112. Termination of call may occur when callee 106 answers the call or caller 104 or callee 106 terminates the call. During playing of an audio file, tone player 504 may also receives media signals, for example DTMF signals, from caller 104.
Tone player 504 is configurable to listen to a request from callee 104 for a particular duration during playing of an audio file. This duration is the listening zone of tone player 504 for the audio file. The listening zone of tone player 504 is different for different audio files. For example, for one audio file the listening zone of tone player 504 may be initial 5 seconds of playing of the audio file while for another audio file, the listening zone may be the last 5 seconds. According to an embodiment, tone player 504 might start listening to request from caller 104 after a prompt message. It should be apparent to a person skilled in the art that configuring listening zone of tone player 504 for an audio file is not a limitation of the invention.
Further, tone player 504 is also configurable to listen to a request in form of a particular set of frequencies, for example frequencies of DTMF signals. For example, caller 104 may press '*' key to generate DTMF signal corresponding to '"' key to send a request. Further tone player 504 may be configured to listen for '*' key DTMF signal for one request and '#' key DTMF signal for another request.
Database 506 comprises audio files which include without limitation songs, RBTs, ringtones, voice messages, advertisements and the like, According to an embodiment, the audio files in database 506 are modified audio files. According to another embodiment, the audio files in database 506 are unprocessed audio files. An audio file in which there is no modification of frequencies is called an unprocessed audio file. According to an embodiment, database 506 further
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comprises audio file information and subscription Information of RBT subscribers. For modified audio file, the audio file information comprises audio file id whereas for an unprocessed audio file, the audio file information additionally comprises listening zone information and modification details for modification of the audio file. The subscription information includes phone number of RBT subscriber, the RBT id of the subscriber and the RBT. The RBT may be stored in commonly known formats, for example, mp3, wav etc,
GUI 508 is a graphical user interface used to analyze an audio file to determine prominence of DTMF signals in the audio file. Using GUI 508, frequencies from frequency spectrum of the audio file which need to be modified could be selected. For example, an audio file comprises frequencies of DTMF signals of key '1', key '2' and key '#'. But only frequency of DTMF signal corresponding to key '1' has to be modified. Using GUI 508 selection of frequencies of DTMF signals of key '1' in the frequency spectrum of the audio file is possible, while the other DTMF signals remain unselected. Also, modification of a specific portion of the audio file is possible. For example, if an audio file is played for 15 seconds, and the modification has to be done for the portion of the audio file, played during first 5 seconds. Using GUI 508, commands for the modification needed in the audio file could be generated.
Frequency processing unit 510 is responsible for modifying audio files. According to an embodiment, modification of an audio file is done at runtime, when a notification to play the audio file is received by request processing system 112. For runtime modification, frequency processing unit 510 receives modification details for modification of an audio file from tone player 504. The runtime modification of an audio file is described in detail in conjunction with FIG. 7. According to another embodiment, static modification of audio files is done. In static modification, the audio files are modified beforehand and modified audio files received are stored in database 506. According to an embodiment, for static modification, frequency processing unit 510 receives the commands for modification of an audio file through GUI 508 and modifies the audio file
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accordingly. The static modification is described in detail in conjunction with FIG. 6A and FIG. 6B.
Frequency processing unit 510 comprises frequency filter 514, pitch shifter 516 and encoder 518. Based on the prominence of DTMF signals in an audio file, the audio file is modified using frequency filter 514 or pitch shifter 516. The audio file after modification is referred to as a modified audio file. The modified audio file has a new frequency spectrum which is different from the frequency spectrum of the audio file. The modification is done such that the new frequency spectrum does not contain frequencies corresponding to DTMF signals in listening zone of tone player 504.
Frequency filter 514 Is a device for modifying audio file by filtering specific frequencies or a frequency band corresponding to one or more DTMF signals from the audio file. According to an embodiment, filtering a DTMF signal from frequency spectrum of the audio file comprises attenuating amplitude of at least one frequency from frequency pair corresponding to the DTMF signal below a threshold amplitude, such that tone player 504 cannot detect the at least one frequency and hence the presence of the DTMF signal in the audio file. According to another embodiment, filtering a DTMF signal from frequency spectrum of the audio file comprises removing at least one frequency from frequency pair corresponding to the DTMF signal. For example, in frequency pair corresponding to DTMF signal of 'V key, if the 1209 Hz is removed or attenuated below threshold, then the DTMF signal of '1' key cannot be detected by tone player 504.
Frequency filter 514 also allows filtering of multiple DTMF signals from audio file. For example, if DTMF signals associated with both key '*' and key '1', are present and GUI 508 generates commands for filtering one frequency corresponding to each of '*' and '1' key, then frequency filter 514 filters the one frequency corresponding to each '*' and '1' key.
According to an embodiment, frequency filter 514 may be a band stop filter. Devices like fully parametric equalizer, graphic equalizer and the like, may
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also be used as band stop filter to modify frequencies of DTMF signal in an audio file. It will be apparent to any person skilled in the art that use of a particular device to attenuate or remove a frequency corresponding to a DTMF signal is not a limitation of the invention.
A band stop filter is an electronic device or a circuit to stop frequencies in a certain band called 'stop band' of the band stop filter. Frequencies outside the stop band are passed without any alteration. Frequencies in the stop band are rejected by attenuating their amplitude. The attenuation may also be complete removal of the frequencies by making their amplitude zero.
Pitch shifter 516 is a device for modifying audio file by shifting the frequency spectrum of the audio file. Shifting the frequency spectrum includes shifting all the frequencies present in the audio file by a pre-specified amount. The audio file after shifting of frequencies is referred to as modified audio file. For example, an audio file has a frequency spectrum with frequencies ranging from 900 Hz to 1500 Hz. The audio file includes frequencies corresponding to '1' key, i.e. frequencies 697 Hz and 1209 Hz. Pitch shifter 516 may shift the frequency spectrum up by 200 Hz. Thus the new frequency spectrum of the modified audio file will have frequencies ranging from 1100 Hz (900 Hz+200 Hz) to 1700 Hz (1500 Hz+ 200 Hz). The frequencies 697 Hz and 1209 Hz after shifting become 397 Hz and 1409 Hz respectively. Thus pitch shifting removes the frequencies corresponding to '1' key from the audio file. The data used in above example is for purpose of mere illustration and should not be used to limit the scope of the invention.
Acconding to an embodiment, the modified audio file after modification is stored in database 506 along with a clip. Encoder 518 creates the clip. The clip comprises listening zone information for the modified audio file. For example, frequency spectrum of the modified audio file has modification for DTMF signal in portion played for first 5 seconds. Hence the listening zone of tone player 504 must also be the initial first 5 seconds of playing of the modified audio file. Also, for example, tone player should listen to frequencies corresponding to '#' DTMF
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key in the listening zone. This information is received from GUI 508 and encoded by encoder 518 in the clip. Thereafter the clip is stored along with the modified audio file.
According to an embodiment the clip may be present in the modified audio file. According to another embodiment, the clip may be a separate file associated with the modified audio file.
FIG. 6A and FIG. 6B are flowcharts describing static modification of an audio file, in accordance with an embodiment of the invention. In the embodiment, audio files are modified and stored in the database.
At step 602, an audio file is imported into database 506. Importing of an audio file occurs when a content provider provides a new audio file to database 506. Importing of an audio file also occurs when a new personalized message or an advertisement is set by an RBT subscriber as RBT .The new audio file is stored in database 506 and later is sent to frequency processing unit 510 for processing.
At step 604, an audio file from database 506 is retrieved and a determination is made using GUI 508 as to whether the audio file contains at least one DTMF signal in its frequency spectrum or not. In case a DTMF signal in the audio file is detected, then step 606 is executed. Also, the listening zone information of the audio file is defined using GUI 508.
At step 606, analysis of the audio file is done using GUI 508. Depending on the prominence of the DTMF signal present in the listening zone of the audio file, at step 606, a decision is made whether the audio file needs frequency shifting or frequency filtering. If the audio file has higher prominence of the DTMF signal, then the audio file is sent for frequency shifting. For example, the listening zone of the audio file may comprise a tune made of only DTMF signals. Hence filtering of any DTMF signal in such an audio file will deteriorate quality of the audio file, hence frequency shifting is required. Using GUI 508 the commands for modification of the audio file are sent to frequency processing unit 510. In case, at step 606 the audio file needs frequency filtering, step 608 is executed.
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At step 608, the audio file is modified by frequency filter 514 to filter the DTMF signal from its frequency spectrum according to the commands received from GUI 508. The commands comprise listening zone information of the audio file and selected frequencies in the frequency spectrum of the audio file which needs to be modified. For example, the commands may be for filtering DTMF signal corresponding to "" key from a portion of the audio file. The portion for example may correspond to first 5 seconds of playing of the audio file. Frequency filter 514 will read the command and will filter at least one frequency corresponding to DTMF signal of '*' key from the listening zone of the audio file.
At step 610, the modified audio file obtained after filtering the DTMF signal from frequency spectrum of the audio file is encoded with a clip which comprises information about the listening zone of tone player 504 for the modified audio file. The listening zone specifies the duration when tone player 504 accepts request during playing of the modified audio file.
At step 612, the modified audio file is stored in database 506.
At step 614, request processing system 112 receives notification to play the modified audio file to caller 104. Based on the notification, application 502 extracts the audio file information from database 506. The audio file information comprises audio file id and relevant information. For example, if the notification is for playing RBT of callee 106, application 502 extracts RBT id of callee 106 from the subscription information of callee 106 stored In database 506. Application 502 forwards the audio file information to tone player 504.
Thereafter at step 616, tone player 504 extracts from database 506, the modified audio file according to the audio file id. Tone player 504 reads the information In the clip associated with the modified audio file. Based on the information, tone player 504 sets its listening zone for the modified audio file. Thereafter tone player 504 plays the modified audio file to caller 104.
When a modified audio file is played, echo occurs resulting in reflection of the modified audio file. Reflected audio file signal will not generate any false request since frequency spectrum of the modified audio file either does not
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contain any DTMF signal or the DTMF signal are so attenuated such that tone player 504 cannot detect the DTMF signal in Its listening zone. Hence generation of false request to request processing system 112 is prevented. Further caller 104 may send requests to request processing system 112 during the listening zone of tone player 504. According to an embodiment, the information about the listening zone may be conveyed to caller 104 through a prompt during playing of the modified audio file. The prompt message signals the caller 104 that the tone player 504 is ready to listen to requests.
In case at step 606, the audio file needs frequency shifting, then step 618 is executed. At step 618, the frequency spectrum of the audio file is shifted to a new frequency spectrum. The information about the new frequency spectrum is present in the clip. Pitch shifter 516 reads the clip and accordingly shifts the frequency spectrum of the audio file to the new frequency spectrum. For example, the clip may comprise information to shift the frequency spectrum of the audio file up or down by 100 Hz. Thus accordingly, the new frequency spectrum may be a lower frequency spectrum or a higher frequency spectrum.
Thereafter step 610 is executed. At step 610 modified audio file is received wherein the modified audio file has the new frequency spectrum.
In case at step 604, no DTMF signal is detected in the audio file, then step 620 is executed. At step 620 the audio file is stored as modified audio file in database 506 and step 614 is executed next.
According to an embodiment, when a user is subscribed to an RBT service, an RBT is set to the RBT subscriber. The present invention provides the RBT subscriber with modified RBT. Also, whenever there is any change in RBT set to the RBT subscriber, RBT system which is request processing system 112 in this case, ensures that the RBT subscriber is provided with modified RBT. For example, if an RBT subscriber wants to change RBT set to the RBT subscriber to an advertisement RBT, RBT system will receive the advertisement RBT in database 506 and will send it to frequency processing unit 510 for modification after receiving commands from GUI 508 for modification of the advertisement
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RBT. Once the advertisement RBT gets modified, it is stored at database 506. Only then, the RBT system will change the RBT subscriber's previous RBT to the modified advertisement RBT, stored in database 506 according to an embodiment. According to another embodiment, the advertisement RBT is modified at runtime. Runtime modification of an audio file is explained in conjunction with FIG. 7.
FIG. 7 is a flowchart describing runtime modification of an audio file, in accordance with an embodiment of the invention.
At step 702, application 502 receives a notification to play an audio file-According to an embodiment the notification may come from caller 104, According to another embodiment the notification may come from MSC 108 when a call connection is established between caller 104 and request processing system 112.
At step 704, audio file information for the audio file is retrieved from database 506 by application 502. The audio file information is then forwarded to tone player 504.
At step 706 tone player 504 retrieves the audio file from database 506 using audio file id in the audio file information. Tone player 504 also receives listening zone information for the audio file from application 502.
At step 708, control unit 512 analyses the audio file information for presence of at least one DTMF signal in the listening zone of audio file. If the audio file has a DTMF signal which tone player 504 will listen in the listening zone, then the audio file and modification information for the audio file are sent to frequency processing unit 510. Thereafter, step 710 is executed.
At step 710, frequency processing unit 510 modifies reads the modification information for the audio file. The modification information gives details about the prominence of the DTMF signal in the audio file. An audio file with higher prominence of DTMF signal requires frequency shifting while with lower prominence requires frequency filtering. The modification information further
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specifies the portion of frequency spectrum of the audio file which is to be modified. The modification information also specifies the set of frequencies to be modified in the specified portion. For example, the modification information may specify that frequencies of DTMF signal corresponding to key '*' should be modified from portion of the audio file corresponding to first 5 seconds of playing of the audio file. So modification is required only for portion corresponding to first 5 seconds of the audio file playing and only for frequencies corresponding to '*' DTMF key.
The modification information may further specify that the whole frequency spectrum of the audio file should be shifted upwards by a particular frequency, for example by 200 Hz.
Depending on the modification information a decision is taken at step 710, whether the audio file should be sent for frequency filtering or frequency shifting. In case the audio file needs frequency filtering, step 712 is executed.
At step 712, frequency filter 514 modifies the audio file according to the modification information received from tone player 504, After modification of the audio file, the modified audio file is sent to tone player 504.
At step 714, tone player 504 adjusts its listening zone for the modified audio file according to the audio file information and plays the modified audio file. While the modified audio file is played, due to echo in the communication channel, a reflection of the modified audio file might be received at tone player 504, But since DTMF signals in the modified audio file are either filtered or shifted to a different frequency band in the listening zpne of tone player 504, hence tone player 504 wilt not detect any false request when tone player 504 is listening. Further caller 104 may send requests to request processing system 112 during the listening zone of tone player 504. According to an embodiment, the information about the listening zone may be conveyed to caller 104 through a prompt during playing of the modified audio file.
In case, at step 710 the audio file needs frequency shifting, then step 716 is executed.
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At step 716, pitch shifter 516 shifts frequency spectrum of the audio file according to the modification information received from tone player 504.
Thereafter at step 714 is executed where the modified audio file is played by tone player 504.
In case at step 708, during analysis of the audio file information, no DTMF signal is found in the audio file, then the audio file is retrieved from database 506, and step 714 is executed.
While example embodiments of the invention have been illustrated and described, it will be clear that the invention is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions and equivalents will be apparent to those skilled in the art without departing from the spirit and scope of the invention as described in the claims.
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WE CLAIM:
1. A method for preventing generation of a false request to a request
processing system during playing of an audio file in a communfcation
network, the method comprising;
a. analyzing the presence of one or more DTMF signals in the audio
file;
b. modifying a set of frequencies present in a listening zone of the
audio file; and
c. playing the modified audio file upon receiving notification;
wherein the generation of false request during playing of modified audio file is prevented due to non-recognition of DTMF signals in the reflected modified audio file by the request processing system.
2. The method of claim 1, wherein the step of modifying a set of frequencies comprises filtering the one or more DTMF signals.
3. The method of claim 2, wherein filtering further comprises removing at least one frequency from frequency pair of the one or more DTMF signal.
4. The method of claim 2, wherein filtering further comprises attenuating amplitude of the at least one DTMF signal below a threshold amplitude.
5. The method of claim 1, wherein the step of modifying a set of frequencies comprises shifting the frequencies present in the audio file.
6. A method for preventing generation of a false request to a request processing system during playing of audio file in a communication network, the request processing system having received a notification for playing the audio file, the method comprising:
a. Retrieving an audio file information of an audio file from a database;
b. modifying a set of frequencies present in a listening zone of the
audio file, the set of frequencies and the listening zone being
identified based on the audio file information; and
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c. playing the modified audio file;
wherein the generation of false request during playing of modified audio file is prevented due to non-recognition of DTMF signals in the reflected modified audio file by the request processing system.
7. The method of claim 6, wherein the step of modifying a set of frequencies comprises filtering the at least one DTMF signal in the audio file.
8. The method of claim 1, wherein the step of modifying a set of frequencies comprises shifting the frequencies present in the audio file.
9. A system for preventing generation of a false request to a request
processing system, the false request being generated during playing of an
audio file in response to presence of one or more DTMF signals in a
listening zone of the audio file, the system comprising:
a. a frequency processing unit, the frequency processing unit
configured to modify the audio file;
b. a tone player, the tone player configured to:
i. receive the modified audio file from the frequency processing
unit; and ii. play the modified audio file.
10. The system in claim 9 further comprises a graphical user interface
configured to receive at least one portion of listening zone information of
the audio file.
11. The system in claim 9, wherein the frequency processing unit comprises a
band stop filter.