Method of preventing clone call of clone terminal

<u style="single">BACKGROUND OF THE INVENTION</u>

<u style="single">Field of the Invention</u>

0001The present invention relates to a method of preventing a clone call of a clone terminal, and more particularly, to a method of preventing a clone call of two or more mobile communication terminals with an identical ESN (electronic serial number) and mobile identification number information in a same base station.

<u style="single">Discussion of the Related Art</u>

0002A mobile communication terminal stores ESN (Electronic serial number) and MIN (mobile identification number) information in an internal memory thereof for easily identifying a terminal and selecting a corresponding terminal in a process of connecting an outgoing/incoming call in relation to a communication service.

0003The mobile communication system manages the ESN and MIN information assigned to each mobile communication terminal by registering the information in a database. In the process of connecting the outgoing/incoming call, the mobile communication system compares the ESN and MIN information of a target terminal with information registered in the database, and performs a call establishment if the information is identical.

0004The ESN and MIN information assigned to the mobile communication terminal may be used in another mobile communication terminal by duplicating the information in another mobile communication terminal. When the outgoing/incoming call is generated, there is a possibility that the outgoing/incoming call is established to a clone terminal with the same ESN and MIN information as that of a legitimate mobile communication terminal. However, in an event that the clone terminal with the same ESN and MIN information is in a different coverage, a clone call is not generated because the call is established only to a first connected terminal even though the call establishment time is the same.

0005If a second terminal tries to establish the call when the outgoing/incoming call is already established to a first terminal, the system is unable to acknowledge the call thereby clone call of two or more mobile terminals is unavailable.

0006However, when the two or more terminals with the same ESN and MIN information and existing in a same base station try the outgoing/incoming call at a same time, the outgoing/incoming call is undetected. In other words, a message from the two or more terminals with the same ESN and MIN information is received by the same base station at the same time, and the base station acknowledges as if there is one mobile communication terminal thereby a call is normally established.

0007Accordingly, the clone call is enabled two or more terminals communizing one traffic channel in the same base station. Therefore, there is a problem that a user of the clone terminal may eavesdrop communication of another user using a legitimate terminal.

0008There is a method of preventing the clone call by using an indigenous A-KEY value of a terminal for preventing source of the clone call of the clone terminal. However, a certifying center is needed for storing the A-KEY value unduplicatable to a database in the mobile communication system, and cost for maintaining the certifying center is expensive. Therefore, the method of preventing the clone call by using an indigenous A-KEY value of a terminal is unused .for economic efficiency <patcit id="pcit0001" dnum="US2001044295A1"><text>US 2001/044295 A1</text></patcit> discloses a mobile communication network comprising: subscriber terminals, a base station, a response request signal transmission unit and a judgment unit. The response request signal transmission unit transmits a response request to a subscriber terminal with a selected MIN and ESN. If a clone terminals exists besides the subscriber terminal, the judgment unit receives a plurality response signals disclosing the presence of the clone terminal.

<u style="single">SUMMARY OF THE INVENTION</u>

0009Accordingly, the present invention is directed to a method of preventing a clone call of a clone terminal that substantially obviates one or more problems due to limitations and disadvantages of the related art.

0010An object of the present invention is to provide a method of preventing eavesdropping by a clone call through a clone terminal.

0011Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. The object is solved by the features of the independent claim.

0012It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

<u style="single">BRIEF DESCRIPTION OF THE DRAWINGS</u>

0013The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings;

0014<figref idref="f0001">FIG. 1</figref> illustrates a flow diagram showing a first embodiment of a method of preventing clone call at a clone terminal in accordance with the present invention.

0015<figref idref="f0002">FIG. 2</figref> illustrates a timing diagram showing a first embodiment of a method of preventing clone call at a clone terminal in accordance with the present invention.

0016<figref idref="f0003">FIG. 3</figref> illustrates a flow diagram of a method of preventing clone call at a clone terminal useful for understanding the invention.

0017<figref idref="f0004">FIG. 4</figref> illustrates a timing diagram of a method of preventing clone call at a clone terminal for better understanding the invention.

0018<figref idref="f0005">FIG. 5</figref> illustrates a diagram of a status request message in <figref idref="f0004">FIG. 4</figref>.

0019<figref idref="f0006">FIG. 6</figref> illustrates a diagram of a status reply message in <figref idref="f0004">FIG. 4</figref>.

0020<figref idref="f0007">FIG. 7</figref> illustrates a flow diagram of a method of preventing clone call at a clone terminal useful for understanding the invention.

0021<figref idref="f0008">FIG. 8</figref> illustrates a timing diagram of a method of preventing clone call at a clone terminal as in <figref idref="f0007">fig. 7</figref>.

0022<figref idref="f0009 f0010">FIG. 9a to FIG. 9b</figref> illustrate a diagram of a parameter search message and a reply message in <figref idref="f0008">FIG. 8</figref>.

<u style="single">DETAILED DESCRIPTION OF THE INVENTION</u>

0023Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

0024The present invention is a method of preventing a clone call by using two terminals with same ESN and MIN information. Accordingly, a following description is an example of a case that a normal terminal and a clone terminal existing in a same coverage try to communicate at a same time. A mobile communication system needs a program for performing a function of managing a call together with a function of detecting clone call.

0025A method of preventing clone call in accordance with the present invention is analyzing a signal message provided from the terminal existing in the same base station and determining an existence of the clone terminal. The signal message used for detecting the clone call is in a various forms. The method is divided into a case of using replay time difference in each terminal.

0026First, a preventing process of the clone terminal using time difference of connect order of the terminal is described with reference to <figref idref="f0001">FIG. 1</figref> and <figref idref="f0002">FIG. 2</figref>. <figref idref="f0001">FIG. 1</figref> illustrates a flow diagram showing a first embodiment of a method of preventing clone call at a clone terminal in accordance with the present invention. <figref idref="f0002">FIG. 2</figref> illustrates a timing diagram showing a first embodiment of a method of preventing clone call at a clone terminal in accordance with the present invention.

0027The process of preventing the clone call of the clone terminal using the incoming response time difference is limited to the incoming call. If there exists the clone terminal with the same ESN and MIN information in one base station, the incoming call management process is almost same from generation of an incoming call to the connect order of the terminal user.

0028In other words, as illustrated in the timing diagram of <figref idref="f0002">FIG. 2</figref>, there is no time difference until paging terminals (MS1, MS2) via the BS (Base station) and performing a series of incoming call management process such as Page response, Channel assignment, BS ACK order, MS ACK order, Service order, Service connect complete such that the terminal remains in waiting (S11).

0029An alert with information is transmitted to a target terminal for the incoming call according to the incoming call management procedure (S12). A called subscriber performs a variety of forms of connect order. In this case, the connect order is transmitted from a called terminal to the base station (S13).

0030When the connect order is received from the called terminal, it is confirmed whether the connect order is received from a second terminal with ESN and MIN information same as the called terminal in a predetermined period of time (S 14).

0031In this case, if there is no connect order of the second terminal with the same ESN and MIN information in the predetermined period of time, a normal incoming call management process is performed. The incoming call is processed for communication between the calling subscriber and the called subscriber (S15).

0032When there are connect orders from the second terminal with the ESN and MIN information at different time intervals (Δ t) in the process of S14, it is acknowledged as the clone call by the clone terminal. Accordingly, the corresponding call is terminated (S17). Desirably, before the call preventing (S17), a notification message is transmitted for notifying existence of the clone terminal with the same ESN and MIN information to the call request caller (S16).

0033After the incoming message is transmitted from the base station to the called terminal, the connect order is transmitted to a corresponding base station at the time the called subscriber presses a speak button (or opens a flip). It is rare that the connect order from different terminals with the same ESN and MIN information is transmitted at the same time. Therefore, when the connect order is received from two or more terminals with the same ESN and MIN information in the predetermined period, it is as if there exists the clone terminal and therefore the corresponding incoming call is terminated. The following is provided for better understanding the invention.

0034There is a method of using the specific information of the terminal for preventing the clone call of the clone terminal. As abovementioned, the terminal specific information is divided into the fixed specific value and the floating specific value.

0035First, the method of preventing the clone call of the clone terminal by using the clone terminal is described referring to <figref idref="f0003 f0004 f0005 f0006">FIG. 3 to FIG. 6</figref>. The fixed specific information of the terminal means a specific hardware of the terminal (i.e., a kind of the terminal) and software version. The method of preventing the clone call considers a point that fixed characteristic information such as hardware and software version information of each terminal may be different from each other although the two or more terminals have the same ESN and MIN information. The clone call process of the fraud terminal using the fixed specific value of the terminal is applied to the outgoing/incoming call.

0036As illustrated in the flow diagram of <figref idref="f0003">FIG. 3</figref>, a basic call process according to the outgoing/incoming call generation is performed (S31), and a status request message for requesting the fixed specific value information is transmitted to the terminal by using the ESN and MIN information of the corresponding outgoing/incoming terminal (S32). Transmission process of a fixed specific value request message is performed a plurality of times. The fixed specific value request message is shown in a record type field 51 as a form of IS-2000 as illustrated in <figref idref="f0005">FIG. 5</figref>. A following table 1 is set values for requesting terminal information to the record type field.

0037<tables id="tabl0001" num="0001"><table frame="all"><title>[Table 1]</title><tgroup cols="3"><colspec colnum="1" colname="col1" colwidth="53mm" /><colspec colnum="2" colname="col2" colwidth="34mm" /><colspec colnum="3" colname="col3" colwidth="39mm" /><thead><row><entry align="center" valign="top">Information record requested</entry><entry align="center" valign="top">Record type (binary)</entry><entry align="center" valign="top">Qual_info_type (binary)</entry></row></thead><tbody><row><entry align="center">Reserved for obsolete Identification</entry><entry align="center">00000110</entry><entry align="center">-</entry></row><row><entry align="center">Call mode</entry><entry align="center">00000111</entry><entry align="center">00000000</entry></row><row><entry align="center">Terminal information</entry><entry align="center">00001000</entry><entry align="center">00000010</entry></row><row><entry align="center">Roaming information</entry><entry align="center">00001001</entry><entry align="center">00000010</entry></row><row><entry align="center">Security status</entry><entry align="center">00001010</entry><entry align="center">00000000</entry></row><row><entry align="center">IMSI</entry><entry align="center">00001100</entry><entry align="center">00000000</entry></row><row><entry align="center">ESN</entry><entry align="center">00001101</entry><entry align="center">00000000</entry></row><row><entry align="center">:</entry><entry align="center">:</entry><entry align="center">:</entry></row></tbody></tgroup></table></tables>

0038The outgoing/incoming target terminal (MS I, MS2) requested to transmit the fixed specific value information of the terminal reads the terminal information stored in the internal memory and transmits the status response message including the fixed specific value to the base station (S33). While or after the status request message is transmitted a plurality of times, the status response message is transmitted. In other words, at the same time the request message is transmitted, the response message from the predetermined terminal is transmitted to the base station. The timing diagram of <figref idref="f0004">FIG. 4</figref> is for helping to understand the transmission process. The status response message is not transmitted only after the transmission of the request message is completed, the transmission of the request message being performed the plurality of times.

0039The status message indicates the record type 61 as illustrated in <figref idref="f0006">FIG. 6</figref>, and a type specific field 61 includes a manufacturer code (MOB_MFG_Code), a model number (MOB_model) and currently used software version (MOB_FIRM_REV) as illustrated in table 2.

0040<tables id="tabl0002" num="0002"><table frame="all"><title>[Table 2]</title><tgroup cols="2"><colspec colnum="1" colname="col1" colwidth="31mm" /><colspec colnum="2" colname="col2" colwidth="22mm" /><thead><row><entry align="center" valign="top">Type Specific Field</entry><entry align="center" valign="top">Length(bits)</entry></row></thead><tbody><row><entry align="center">MOB_P_REV</entry><entry align="center">8</entry></row><row><entry align="center">MOB_MFG_Code</entry><entry align="center">8</entry></row><row><entry align="center">MOB_Model</entry><entry align="center">8</entry></row><row><entry align="center">MOB_FIRM_REV</entry><entry align="center">16</entry></row><row><entry align="center">SCM</entry><entry align="center">8</entry></row><row><entry align="center">Local_CTRL</entry><entry align="center">1</entry></row><row><entry align="center">Slot_cycle_index</entry><entry align="center">3</entry></row><row><entry align="center">:</entry><entry align="center">:</entry></row></tbody></tgroup></table></tables>

0041In this case, transmission (response) process of the request message and the status message of the fixed specific value information of the terminal is performed the plurality of times for receiving at least one response at a minimum from an individual terminal with reference to a case that there are two or more clone terminals.

0042Whether the clone call is placed from the clone terminal is determined by analyzing the fixed specific value received from the terminal. There are two methods for determining whether the clone call is placed from the clone terminal by analyzing the fixed specific value. A first method is comparing the received fixed specific value with the fixed specific value stored in the database in the system. Not only the clone call but also a single call made by the clone terminal is prevented by comparing whether the terminal specific value information stored in the database is the same as the received terminal specific value information.

0043A second method is confirming whether the clone call is tried from the clone terminal with the same ESN and MIN information by comparing whether the received specific values are the same each other (S34).

0044If the received terminal specific values are the same each other, it is confirmed that the clone terminal with the same ESN and MIN information does not exist. In this case, the normal outgoing/incoming call management is performed so as to process communication between the calling subscribers (S35).

0045However, if the received terminal specific values are not the same each other, it is judged that the outgoing/incoming call is tried from the clone terminal. A guide message about preventing the clone call of the clone terminal is transmitted to all call-established terminals (S36) and corresponding outgoing/incoming call is terminated (S37).

0046The method of preventing the clone call of the clone terminal by using the terminal specific value and the floating specific value is described referring to <figref idref="f0007 f0008 f0009 f0010">FIG. 7 to FIG.9b</figref>. The method is for preventing the clone call of the two or more clone terminals with the same fixed specific value, that is, the same ESN and MIN information, and same hardware and software version. The floating information according to the terminal operation means reception frequency information of an overhead message (a configuration parameter and an access parameter message) having system information transmitted for establishing the call from time the terminal searches the base station after the power of the terminal is on to the time the terminal is changed into a waiting mode.

0047<figref idref="f0007">FIG. 7</figref> illustrates a flow diagram of a method of preventing clone call at a clone terminal <figref idref="f0008">FIG. 8</figref> illustrates a further timing diagram of a method of preventing clone call at a clone terminal. <figref idref="f0008">FIG. 8</figref> illustrates an example of incoming call management.

0048First, the basic call management process (Paging, Page response, Channel assignment, BS ACK order, MS ACK order, Service connect, Service connect complete) is performed (S71). A retrieve parameter message for requesting the operation change information by using the ESN and MIN information of the incoming/outgoing target terminal is repeatedly transmitted. Reason why the information request message is repeatedly transmitted is the same as that of the status request message transmission. In other words, it is for receiving at least one response from at least one individual terminal with regard to the case there exist two or more clone terminals.

0049<figref idref="f0009">FIG. 9a</figref> illustrates a diagram of a retrieve parameter message defined in IS-2000. To the parameter search message including traffic that is a signal of an upper layer (L3), a parameter ID value about paging and access channel related to the operation change information of the terminal is set and transmitted so as to request the operation change information to the corresponding outgoing/incoming target terminal.

0050Then, the outgoing/incoming target terminal being requested for the operation change information retrieves the operation change information such as the paging and the access channel related parameter information and repeatedly transmits the information to the base station, the operation change information stored and managed in a separate memory. The parameter response message is transmitted while or after the retrieve parameter message is transmitted a plurality of times. In other words, at the same time the request message is transmitted from a predetermined terminal, the response message is transmitted to the base station. The timing diagram of <figref idref="f0008">FIG. 8</figref> is to help understanding the process and the transmission of the request message is carried out after the transmission of the request message is completely carried out the plurality of times.

0051By using the parameter response message defined in IS-2000 illustrated in <figref idref="f0010">FIG. 9B</figref>, the operation change information of the terminal is transmitted. As illustrated in following table 3, the operation change information such as paging and access channel information (PAG_#, ACC_#; #=1, 2, ..., N) and the system time information (OTHER_SYS_TIME) retrieved from the internal memory is set into the parameter ID and the parameter information field of the parameter response message and transmitted.

0052<tables id="tabl0003" num="0003"><table frame="all"><title>[Table 3]</title><tgroup cols="6"><colspec colnum="1" colname="col1" colwidth="27mm" /><colspec colnum="2" colname="col2" colwidth="28mm" /><colspec colnum="3" colname="col3" colwidth="22mm" /><colspec colnum="4" colname="col4" colwidth="31mm" /><colspec colnum="5" colname="col5" colwidth="29mm" /><colspec colnum="6" colname="col6" colwidth="31mm" /><thead><row valign="middle"><entry align="center">Parameter Identifier</entry><entry align="center">Value of Parameter_ID (decimal)</entry><entry align="center">Length (bits)</entry><entry align="center">Support Required</entry><entry align="center">Settable Parameter</entry><entry align="center">Reference Section</entry></row></thead><tbody><row><entry align="center">:</entry><entry align="center">:</entry><entry align="center">:</entry><entry align="center">:</entry><entry align="center">:</entry><entry align="center">:</entry></row><row><entry align="center">PAG_1</entry><entry align="center">29</entry><entry align="center">24</entry><entry align="center">Y</entry><entry align="center">Y</entry><entry align="center">[4]</entry></row><row><entry align="center">PAG_2</entry><entry align="center">30</entry><entry align="center">24</entry><entry align="center">Y</entry><entry align="center">Y</entry><entry align="center">[4]</entry></row><row><entry align="center">PAG_3</entry><entry align="center">31</entry><entry align="center">16</entry><entry align="center">Y</entry><entry align="center">Y</entry><entry align="center">[4]</entry></row><row><entry align="center">PAG_4</entry><entry align="center">32</entry><entry align="center">24</entry><entry align="center">Y</entry><entry align="center">Y</entry><entry align="center">[4]</entry></row><row><entry align="center">PAG_5</entry><entry align="center">33</entry><entry align="center">24</entry><entry align="center">Y</entry><entry align="center">Y</entry><entry align="center">[4]</entry></row><row><entry align="center">PAG_6</entry><entry align="center">34</entry><entry align="center">16</entry><entry align="center">Y</entry><entry align="center">Y</entry><entry align="center">2.4</entry></row><row><entry align="center">PAG_7</entry><entry align="center">35</entry><entry align="center">16</entry><entry align="center">Y</entry><entry align="center">Y</entry><entry align="center">2.4</entry></row><row><entry align="center">ACC_1</entry><entry align="center">36</entry><entry align="center">16</entry><entry align="center">Y</entry><entry align="center">Y</entry><entry align="center">[4]</entry></row><row><entry align="center">ACC_2</entry><entry align="center">37</entry><entry align="center">16</entry><entry align="center">Y</entry><entry align="center">Y</entry><entry align="center">[4]</entry></row><row><entry align="center">ACC_3</entry><entry align="center">38</entry><entry align="center">16</entry><entry align="center">Y</entry><entry align="center">Y</entry><entry align="center">[4]</entry></row><row><entry align="center">ACC_4</entry><entry align="center">39</entry><entry align="center">16</entry><entry align="center">Y</entry><entry align="center">Y</entry><entry align="center">[4]</entry></row><row><entry align="center">ACK_5</entry><entry align="center">40</entry><entry align="center">16</entry><entry align="center">Y</entry><entry align="center">Y</entry><entry align="center">[4]</entry></row><row><entry align="center">ACC_6</entry><entry align="center">41</entry><entry align="center">16</entry><entry align="center">Y</entry><entry align="center">Y</entry><entry align="center">[4]</entry></row><row><entry align="center">ACC_7</entry><entry align="center">42</entry><entry align="center">16</entry><entry align="center">Y</entry><entry align="center">Y</entry><entry align="center">[4]</entry></row><row><entry align="center">ACC_8</entry><entry align="center">43</entry><entry align="center">16</entry><entry align="center">Y</entry><entry align="center">Y</entry><entry align="center">[4]</entry></row><row><entry align="center">:</entry><entry align="center">:</entry><entry align="center">:</entry><entry align="center">:</entry><entry align="center">:</entry><entry align="center">:</entry></row><row><entry align="center">Other_sys_time</entry><entry align="center">49</entry><entry align="center">3</entry><entry align="center">Y</entry><entry align="center">N</entry><entry align="center">2.4</entry></row></tbody></tgroup></table></tables>

0053The paging and access channel information (PAG_N, ACC_N) is compared with system time information. The paging and access channel information indicating total reception frequency of each kind of overhead message among the operation change information included in the parameter response message repeatedly received from the terminal with the same ESN and MIN information (S74).

0054When the information is the same, the normal call management process is performed (S75). When different information exists, it is assumed to be the clone call of the clone terminal, and the corresponding outgoing/incoming call is terminated (S77). A guide message transmission process is preceded (S76).

0055The embodiment according to the present invention is not limited to the abovementioned description, and it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention. For example, as aforementioned, the method of detecting and preventing the clone call by using the call response difference and the method of preventing the clone call by using each terminal management information are realized individually, or each of the methods is carried out at a same time or in order.

0056Each of method of preventing the clone call is activated/deactivated by a system operator or a terminal user. As aforementioned, the present invention detects the clone call attempted by two or more terminals with the same ESN and MIN information by using the incoming response time difference of the terminals processing the incoming call within one base station of the mobile communication so as to block the clone call of the clone terminal in the same base station.

0057The present invention detects the attempt of the clone call by two or more communication with the same ESN and MIN information by using the fixed characteristic information managed by each terminal processing the outgoing/incoming call in one base station of the mobile communication system or the floating information according to the terminal operation so as to block the clone call of the clone terminal in the same base station.

0058It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims.