Method for informing a subscriber of a mobile telephony network about missed calls

[0001] The subject of the invention is a method of notifying a subscriber of a cellular network about missed calls.

[0002] The SMS notification service for missed calls is known and is, for example, offered on the D1 mobile network by the operator T-Mobile Germany under the name "SMS Lost Calls". This service always operates when the user's mobile phone is switched off or out of range and no call switching has been activated, e.g. to a voice mailbox. If the subscriber is called in such conditions, the call is registered in the cellular network. As soon as the called subscriber switches on his mobile phone again, he will be notified via SMS about missed calls that have taken place in the meantime. Preferably, each calling number is given once in each SMS. For example, the information always includes only the last five calling numbers, with each calling number being kept in memory for a limited time only. Of course, this method works only if the subscriber provides his phone number, i.e. activated the CLI (Calling Line Identification) command to reveal his phone number. If the subscriber has blocked the disclosure of his telephone number, the called subscriber cannot be informed about the identity of the caller.

[0003] WO 03/077570 A1 discloses a method of notifying a subscriber of a cellular network of a call from another subscriber while the cellphone of the given subscriber was turned off or was outside the range of the cellular network. Informing takes place via the subscriber's cell phone as soon as the cell phone is logged back into the cell network, the message comprising at least the subscriber's phone number of the unsuccessful call. The case of the CLI (Calling Line Identification) command line for revealing the identity of the calling subscriber is not included.

[0004] Description US 6 748 058 B1 relates to a caller identification system which, in the event of a subscriber blocking by the CLIR (Calling Line Identification Restriction) command line, the disclosed subscriber number causes the cellular network to automatically send a message to the blocking subscriber requesting the temporary release of revealing its number telephone only for this call, which will allow the subscriber to provide the calling number.

[0005] The object of the invention is to provide a method for notifying a subscriber of a cellular network of missed calls, which will create the possibility of notifying the subscriber also of phone calls with blocked disclosure of the calling telephone number.

[0006] This task is solved by the method according to the invention with the features of claim 1. 1.

[0007] Further advantageous solutions and developments of the method according to the invention result from the dependent claims.

[0008] The invention is based on dialogue control of communication between the subscriber and his voice box. Dialog control consists primarily of voice information from the voice box to the subscriber's cell phone and DTMF (Dual Tone Multifrequency Signaling) communication from the subscriber's cell phone to the voice box. This dialogue control takes place primarily before the through connection is made and the Charging Records are made in the MSC (Mobile Switching Center). Such a dialogue can be used in particular to request the caller to disclose his blocked cell phone number before making a call to the billing record.

[0009] Until now, it was not possible to carry out a dialogue between the cellular telephone exchange and the voice mailbox before making the target connection, and thus also the exchange of information. Such a dialogue between the subscriber and the voice mailbox is, however, necessary when one wants to obtain the subscriber's consent, e.g. for transferring a call number or making a call with a record for billing.

[0010] According to the invention, the ISUP signaling (ISDN User Part) signaling is changed between an MSC (Mobile Switching Center) cellular telephone and a voice mailbox. The ISUP signaling protocol (ISDN User Part) is a specific part of the ISDN (Integrated Services Digital Network) digital network for the transmission of additional information through the signaling channel between control panels. According to the invention, another change of standard ISUP information is required by the subscriber or voice mailbox. In addition, it is necessary that the parameters in the individual ISUP information are set appropriately to the dialogue between the subscriber and the voice mailbox.

[0011] The method according to the invention can be implemented not only under CFNREACH (call forwarding not reachable) conditions, but also in all other unconditional call forwardings, such as CFBUSY (call forwarding busy) and CFNREPLY (call forwarding no reply).

[0012] The method according to the invention may be implemented in particular in the form of a computer program whose program code is executed on the computer of a cellular network element.

[0013] Based on Fig. 1, the calling and signaling process will be explained in more detail in a preferred embodiment of the invention.

[0014] For the initial situation, it is assumed that the caller, e.g. a subscriber to a public communication network, wants to get a connection with another subscriber, e.g. a subscriber to the cellular network, hereinafter also called the called. For this purpose, the caller dials the desired number of the called.

[0015] According to Figure 1, in the first step 1), the connection request is forwarded in the form of IAM (Initial Address Message) information to the respective (intermediate) GMSC (Gateway Mobile Switching Center). information

IAM assures, among other things, that the appropriate utility channel for the requested call service is enabled and contains service data, utility channel characteristics and service features. The IAM information includes, among others, the MSISDN call number of the called cell phone, consisting of the country code (CC) of the national area code (NDC) and the subscriber number (SN). MSISDN is analyzed by the control panel. The caller can be both a subscriber to fixed network (PSTN / ISDN) and cellular network (PLMN).

In accordance with steps 2) and 3), the following routing procedure is now usually carried out for a given call: the GMSC sends the so-called SRI information to the HLRB home register of the called subscriber. SRI (Send Routing Information) information is MAP information, which the control panel sends to the called HLRB home register called in order to receive appropriate routing information from it, e.g. place of stay of the called, in order to forward the request to call the desired subscriber. In the assumed case, the called subscriber has turned off his cell phone or is not connected to his cell network. This situation is known in the parent HLRB registry. The called subscriber has turned off his mobile phone, for example. In addition, it is also known (detach / attach status) that the called subscriber has not activated his voice mailbox (answering machine function) in the event of "unreachability", as a result the caller cannot leave any message in the voice mailbox. Because the called subscriber does not answer and has not switched the call to the voice mailbox, the HLRB home register recognizes the following condition: Call Forwarding Not Reachable (CFNREACH), i.e. in the event of no reachability the call is forwarded.

[0017] In the case of CFNR (Call Forwarding No Reply), the call is forwarded if the called party does not answer. This feature of the service allows the operator to switch calls if the subscriber is not logged in (detached). In this case, the HLRB register returns to the GMSC the SRI confirmation information containing the general call number for switching the CFD FTNO call (Call Forwarding Forwarded to No.) to which the call is to be forwarded (for example "0" NDC "CC" 12345678), with NDC = national area code, CC = a non-selectable "C" sign twice so that the customer cannot choose the service himself and to recognize the service in the Voice-Mail VMS / CCS system. The GMSC will now transfer the call to the FTNO call number. The corresponding call number for call switching must, of course, be previously registered in the appropriate routing database. Received number "0" NDC "CC" 12345678 is now forwarded in SRI information to the HLRB home registry. This number belongs to the Voice-Mail VMS / CCS system. After receiving SRI information by the HLRB home registry in a special MSISDN, i.e. the above mailbox number, the routing address of the subscriber's Voice-Mail system is calculated depending on the NDC national code and in accordance with the concept of MPN (Mobile Number Portability). The home HLRB register finds the address of the Voice-Mail VMS / CCS system.

[0018] In step 4), the GMSC mobile exchange now sends IAM information to the subscriber's Voice-Mail system: IAM information includes the address (call number) of the calling subscriber (A), the address of the called subscriber (MS B) and the address of the called Voice-Mail system CVMS / CCS. System

Voice-Mail VMS / CCS dials A and MS B numbers and stores the A number of the calling MS number B. The Voice-Mail VMS / CCS system identifies the situation that caller A has blocked (CLIR) the disclosure of his call number (CLI). If the caller's CLI is not available, the Voice-Mail system deactivates the call and creates a connection to the called party with a special

Release Cause.

[0019] Now, in the case of blocked disclosure of the calling CLI subscriber according to the invention in step 5), confirmation information (Connect Message or CON Message) is sent to the GMSC via the Voice-Mail VMS / CCS system and the call settlement in the MSC is started.

[0020] The Voice-Mail VMS / MSU system set up specifically for the service according to the invention is now activated and by means of a special speaking system in accordance with step 6) the caller A is informed and called to temporarily provide his call number CLI for this call. At the same time, he is called by VMS / MSU to implement this release by activating the appropriate button sequence on the mobile phone. The sequence of buttons performed by the subscriber is sent back in the two-tone DTMF system to the Voice-Mail VMS / MSU system. In the event that subscriber A does not send any reply, and therefore does not agree to the disclosure of his telephone number, the call is interrupted after the pre-set time T1. Continued according to step 9) and the subscriber's VoiceMail VMS / CCS system sends the release message to dismantle the connection. In this case, the GMSC in accordance with step 10) responds with RLC information and confirms the removal of the connection.

[0021] If the calling subscriber agrees to temporarily disclose his telephone number for that call, then in accordance with step 7) he may, within the time T1, perform confirmation of the telephone number transfer by running the sequence of DTMF buttons. DTMF information is transmitted to a special Voice-Mail VMS / MSU system.

[0022] In step 8) in the second optional information a confirmation is sent to the subscriber from the special Voice-Mail-System VMS / MSU system about the successful transfer of his telephone number. The Voice-Mail VMS / CCS system of the subscriber is now able to identify the caller based on the provided call number and inform the called party about the unsuccessful call by providing the caller's phone number. Now the connection is dismantled according to steps 9) and 10) above.