MXPA99006871A - Telephone callback detector. - Google Patents

Abstract

A callback system detector (300) is connected between a toll trunk (200) and a local switched telephone network (100) for detecting and discouraging operation of a toll callback system wherein incoming calls on the toll trunk line are employed as a gateway for a user of the switched telephone network (100) to place calls within a remote telephone network and thus avoid tariffs charged by the local network (100) for outgoing calls to the remote network. The callback system detector is configured to determine the presence, within an incoming call on the toll trunk (200), of a condition indicative of operation of such a callback system. Such a condition may be defined as incoming dial or ringing tones on the toll trunk, or as outgoing dual-tone multi-frequency (DTMF) tones on the toll trunk. In order to allow such tones to be transmitted in the normal course of a call that may legitimately employ such tones, operation of the callback detector may advantageously be limited to a predetermined time period defining an initial call interval. The callback detector (300) may be configured to disrupt communication within the call upon detection of the condition, or further may be configured to cause disconnection of the call or assessment of a billing charge to the local recipient of the call.

Description

AUTOMATIC TELEPHONE CALL DETECTOR BACKGROUND OF THE INVENTION In some regions, there may be a wide disparity in international telephone rates and the applicable rate often depends on the country from which a call originates. The rates of international settlements between long distance carriers are sometimes set in such a way that it may be significantly less expensive to place a call to Country A from Country B, rather than placing a call to Country B from the Country ¡A. When there is such a tariff disparity, a person in Country A, for example, may have a service in Country B to call him and then allow him to dial a call through the telephone network of Country B to his desired destination. The caller in Country A then pays the lowest rate for a call that originates in Country B and avoids the highest rate that would apply if he had placed a normal long distance call from Country A. In another environment It could be less expensive to place a call between Countries A and C, by establishing two simultaneous calls, one from Country B to Country A, as described above and one from Country B to Country C. These two calls could: then interconnect within Country B to make an international connection between Countries A and C, but at the lowest rate available. in Country B. In some countries, the user of such "automatic call" services is illegal or is at least a loss of the income of the international long distance carrier in the country with the highest rate. Therefore, it would be desirable to detect such call patterns and either block the call or apply an appropriate surcharge to the person calling from the country with the highest rate to discourage such techniques. SUMMARY OF THE INVENTION The problems described above associated with the current state of the art in international telecommunications are solved to a greater degree by an automatic call detection system, in accordance with the present invention. A switched telephone system has an international trunk line to carry voice signals to another country and a signaling channel associated with the interurban line. A signaling monitor connects to the signaling channel to monitor signals on the channel and detect signals that are transmitted from a location at a remote end of the international trunk line. The signaling monitor provides a remote call indication signal when that condition is detected. The automatic call detector is operatively connected to the international trunk line. The automatic call detector is also connected to the signaling monitor to receive the remote call indication signal. When the auto call detector receives a remote call indication signal it begins to monitor a corresponding channel on the trunk line for a signal that is indicative of a call leaving an automatic call service. When such a signal is detected, the automatic call detector either blocks the call or sends an automatic call indication signal to the central switching system or billing system of the telecommunications company for appropriate action. Such action would include blocking the call or applying an appropriate surcharge to the caller's account. DETAILED DESCRIPTION Referring now to Figure 1, a telecommunications network 100 is shown in a first country (Country A) having international trunk lines 200 connected to it to transmit calls to and receive calls from another country (Country B). Associated with the international trunk lines 200 is a signaling channel 600. The signaling channel 600 is incorporated as a standard or non-standard signaling channel, such as, but is not limited to, the international signaling system 5, 6 or 7. The international interurban lines are connected through an automatic call detector 300 and the signaling channel 600 is connected through a signaling monitor 500. The signaling monitor 500 is preferably incorporated into the switched telephone network 100. The signaling monitor 500 is connected to the automatic call detector 300 and the automatic call detector 300 is connected to the switching system or billing system 400 of the carrier. international long distance in Country A. Signaling monitor 500 monitors signaling channel 600 for an incoming call, i.e. a call originating from the remote end of international trunk lines 200. In this modality, the call could originate from Country B, which has a lower international long distance rate for calls to the P ais A in relation to the rate for calls to Country B from Country A. When such a call is detected, signaling monitor 500 communicates that information to automatic call detector 300 and identifies the particular channel receiving the incoming call. The automatic call detector then monitors the channel specified for any of the '>; following counter conditions within a pre-selected initial period of the call: (1) an incoming dial tone; (2) outgoing dual tone multiple frequency (DTMF) signaling; or (3) an incoming call tone 5. An incoming dial tone would not normally be present on an incoming call. However, it is often used by automatic calling systems to indicate to the subscriber that he can make an automatic call to the originating party. An automatic call subscriber 10 often uses DTMF signals to signal his or her desired destination of call to the automatic calling system. Although the subscriber uses DTMF signaling to control voice response systems such as voice mail, such signaling is not normally used during the initial period of an incoming call, defined as a predetermined time interval from the start of the call. In an "automatic" telephone call, an incoming call tone from the selected destination telephone 20 indicates to the automatic call subscriber that the automatic call is being attempted. Although it is possible to obtain an incoming call tone or an incoming call under other conditions, such as call redirection, those conditions would normally not be present during the initial call period.

When the automatic call detector 300 detects any of the above conditions, the call is determined to be an "automatic" call. At this point, the automatic call detector 300 can force the termination or interruption of the call by any number of methods, such as interrupting the conversation path between the switched network 100 and the international junction lines 200. Such an interruption may include the inserting a free code in both directions in the way of conversation or the insertion of a tone of "all busy lines of union" or another tone in the way of conversation. Alternatively, the presence of an automatic call may be communicated by the automatic call detector 300 to the switching or charging system of the telephone company 400, such that the call may be disconnected or blocked or for an appropriate surcharge to be applied to the account. Subscriber's telephone charge. The signaling between the automatic call detector 300, the signaling monitor 500 and the billing or switching system 400 is preferably sent through dedicated connections or within the signaling procedure of the talk channel 200.

Claims (19)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as novelty and therefore the content of the following claims is claimed as property. An apparatus for preventing the operation of an automatic calling system operating between a switched telephone network and a line of interurban links having talk channels and a signaling channel, comprising: a signaling monitor connected to the signaling channel of the trunk line and configured to provide an indication that an incoming call is received on a corresponding talk channel of the trunk line; an automatic call detector connected to talk channels of the interurban line and responding to the indication provided by the signaling monitor to detect, within the corresponding conversation channel, a condition indicating the operation of the automatic call system using the conversation channel. The apparatus according to claim 1, characterized in that the automatic call detector is configured to interrupt the communication in the conversation channel in the detection of said condition. The apparatus according to claim 2, characterized in that said automatic call detector is configured to interrupt the conversation channel by at least one of (i) providing a free code to the conversation channel, (ii) providing a busy signal to the channel of conversation and (iii) provide an audible tone to the conversation channel. 4. . The apparatus according to claim 1, characterized in that said automatic call detector is configured to detect said condition as at least one of (i) an incoming dial tone in the conversation channel, (ii) an incoming call tone in the channel of conversation and (iii) outgoing DTMF tones in the conversation channel. The apparatus according to claim 4, characterized in that said automatic call detector is configured to detect said condition for a predetermined period of time limited to a predetermined initial call interval. The apparatus according to claim 1, characterized in that a switching system is connected to the switched telephone network and wherein said automatic call detector is connected to said switching system and further configured to provide a signal to the switching system to disconnect the incoming call in the detection of said condition. 7. The apparatus according to claim 6, characterized in that said automatic call detector is configured to detect said condition as at least one of (i) an incoming dial tone in the conversation channel, (ii) an incoming call tone in the channel of conversation and (iii) outgoing DTMF tones in the conversation channel. The apparatus according to claim 7, characterized in that said automatic call detector is configured to detect said condition for a predetermined period of time limited to a predetermined initial call interval. The apparatus according to claim 1, characterized in that a billing system is connected to the switched telephone network and wherein said automatic call detector is connected to said billing system and further configured to provide a signal to the billing system to apply a default charge to receive the incoming call. The apparatus according to claim 9, characterized in that said automatic call detector is configured to detect said condition as at least one of (i) an incoming dial tone in the conversation channel, (ii) an incoming call tone- in the conversation channel and (iii) outgoing DTMF tones in the conversation channel. The apparatus according to claim 10, characterized in that said automatic call detector is configured to detect said condition for a predetermined period of time limited to a predetermined initial call interval. 12. The apparatus according to claim 1, characterized in that said automatic call detector is configured to detect said condition as at least one of (i) an incoming dial tone in the conversation channel, (ii) an incoming call tone in the conversation channel and (iii) outgoing DTMF tones in the conversation channel. The apparatus according to claim 1, characterized in that said automatic call detector is configured to detect said condition for a predetermined period of time limited to a predetermined initial call interval. A method for preventing the operation of an automatic call system between a line of interurban links and a switched telephone network, comprising the steps of: detecting the start of an incoming call on a channel of said interurban line; monitoring said channel of said line of inter-urban links for a condition indicative of the operation of the automatic calling system; and discourage the subsequent operation of the automatic calling system. The method according to claim 14, characterized in that said step of monitoring comprises the step of: determining the presence of said condition as one of (i) an incoming dial tone in the channel, (ii) an incoming call tone in the channel and (iii) outgoing DTMF tones in the channel. The method according to claim 15, characterized in that said determining step is executed for a predetermined period of time limited to a predetermined initial calling interval. The method according to claim 14, characterized in that said discouragement step comprises at least one of (i) interrupting communication in the channel, (ii) providing a fcode to the channel, (iii) providing a busy signal to the channel , (iv) provide an audible tone to the conversation channel, (v) disconnect the call and (vi) value a charge premium for receipt of the incoming call. 16. An apparatus for the connection between an interurban link and a switched telephone network, comprising: a control input for receiving an identification of an incoming call on the interurban link; a condition detector for detecting a condition of the incoming call indicative of the operation of an automatic calling system; and an output for signaling the detection of said condition. The apparatus according to claim 16, characterized in that said condition detector is configured to detect at least one of (i) an incoming dial tone at the interurban links, (ii) a 'incoming call tone in the interurban links and (iii) outgoing DTMF tones in the interurban links. 18. The device according to. claim 17, characterized in that said condition detector is configured to 'detect said condition for a predetermined period of time limited to a predetermined initial call interval. The apparatus according to claim 16, characterized in that it also comprises means for interrupting ... the communication in the inter-urban link in response to the detection of said condition. SUMMARY An automatic call system detector (300) is connected between an interurban link (200) and a local switched telephone network (100) to detect and discourage the operation of an interurban automatic calling system where incoming calls on the line of intercity links are used as a gateway for a user of. the switched telephone network (100) for placing calls within a remote telephone network and thus avoiding tariffs charged by the local network (100) for issuing calls to the remote network. The automatic call system detector is configured to determine the presence, within an incoming call in the interurban link (200) of a condition indicative of the operation of such an automatic calling system. Such a condition can be defined as incoming call or dial tones in it; intercity link or as dual tone multiple frequency tones outgoing on the interurban link. In order to allow such tones to be transmitted in the normal course of a call that can legitimately employ such tones, the operation of the automatic call detector can be limited to a predetermined period of time defining an initial call interval. . The automatic call detector (300) may be configured to interrupt communication within the call at condition detection or may be further configured to cause the call to be disconnected or a billing charge to be assessed for local receipt of the call.