Abstract:
The invention concerns a method of providing an improved call forwarding service in a telecommunications network, and a network unit and a computer program product to execute this method. A call initiated by a caller ( 10 ) to a first callee ( 21 ) is consecutively forwarded, starting from the first callee ( 21 ), to one or more further interlinked callees ( 22, 23 ), thereby forming a call forwarding chain ( 401, 402 ). A set of data is added to the call, the data comprising an identifier of each of the callees ( 21, 22, 23 ) involved in the call forwarding chain ( 401, 402 ) and an address associated with a respective message memory ( 210, 220, 230 ) assigned to each of the callees ( 21, 22, 23 ) involved in the call forwarding chain ( 401, 402 ). When the call is forwarded to the message memory ( 230 ) assigned to a last callee ( 23 ) of the call forwarding chain ( 401, 402 ), the caller ( 10 ) is prompted to provide a message to be stored in one or more of the message memories ( 210, 220, 230 ). From the set of data one or more of the addresses associated with the message memories ( 210, 220, 230 ) are retrieved. And the message received from the caller ( 10 ) is delivered to one or more of the message memories ( 210, 220, 230 ) by routing the message to the retrieved one or more addresses.

Description:
The invention is based on a priority application EP 07 291 086.2 which is hereby incorporated by reference. 
   TECHNICAL FIELD 
   The present invention relates to a method of providing an improved call forwarding service in a telecommunications network, and a network unit and a computer program product to execute said method. 
   BACKGROUND OF THE INVENTION 
   In current telecommunications systems, a subscriber who has activated an automatic call forwarding to his voice mailbox is the only one who may access a voice message left by a caller in the mailbox. If a caller is forwarded by a call forwarding service activated by a callee to a third party callee, and forwarded again by a call forwarding service activated by the third party callee to a forth party callee, thus forming a call forwarding chain, the caller may leave a message only in the mailbox of the forth party callee. Thus, the precedent callees of the call forwarding chain, especially the first callee where the call actually was destined to, will not be able to access the message left by the caller and retrieve the information contained. 
   US 2004/0005045 A1 describes call forwarding services in an Advanced Intelligent Network (=AIN). A subscriber connected to a communications network, including the Internet and other packet switched type data networks, is enabled to customize and execute the call forwarding services, with near real-time access to the service data. That prior art concerns only the subscriber&#39;s setting of the call forwarding, not a caller encountering interlinked call forwarding after dialing a callee&#39;s number. 
   SUMMARY OF THE INVENTION 
   It is the object of the present invention to provide an improved method of call forwarding. 
   The object of the present invention is achieved by a method of providing an improved call forwarding service in a telecommunications network, wherein a call initiated by a caller to a first callee is consecutively forwarded, starting from the first callee, to one or more further interlinked callees, thereby forming a call forwarding chain, wherein the method comprises the steps of adding a set of data to the call, the data comprising an identifier of each of the callees involved in the call forwarding chain and an address associated with a respective message memory assigned to each of the callees involved in the call forwarding chain, prompting, when the call is forwarded to the message memory assigned to a last callee of the call forwarding chain, the caller to provide a message to be stored in one or more of the message memories, retrieving from the set of data one or more of the addresses associated with the message memories, and delivering the message received from the caller to one or more of the message memories by routing the message to the retrieved one or more addresses. Furthermore, the object of the present invention is achieved by a network entity for providing an improved call forwarding service in a telecommunications network, wherein a call initiated by a caller to a first callee is consecutively forwarded, starting from the first callee, to one or more further interlinked callees, thereby forming a call forwarding chain, wherein the network entity comprises a control unit adapted to add a data set to the call, the data comprising an identifier of each of the callees involved in the call forwarding chain and an address associated with a respective message memory assigned to each of the callees involved in the call forwarding chain, prompt, when the call is forwarded to the message memory assigned to a last callee of the call forwarding chain, the caller to provide a message to be stored in one or more of the message memories, retrieve from the data set one or more of the addresses associated with the message memories, and deliver the message received from the caller to one or more of the message memories by routing the message to the retrieved one or more addresses. And the object of the present invention is achieved by a computer program product providing an improved call forwarding service in a telecommunications network, wherein a call initiated by a caller to a first callee is consecutively forwarded, starting from the first callee, to one or more further interlinked callees, thereby forming a call forwarding chain, wherein the computer program product, when executed by a network entity, performs the steps of adding a set of data to the call, the data comprising an identifier of each of the callees involved in the call forwarding chain and an address associated with a respective message memory assigned to each of the callees involved in the call forwarding chain, prompting, when the call is forwarded to the message memory assigned to a last callee of the call forwarding chain, the caller to provide a message to be stored in one or more of the message memories, retrieving from the set of data one or more of the addresses associated with the message memories, and delivering the message received from the caller to one or more of the message memories by routing the message to the retrieved one or more addresses. 
   Generally, the invention improves the reachability of a callee. 
   The invention allows a caller faced with a call forwarding chain to have his message delivered not only to the last callee of the call forwarding chain but also to one or more other callees of the call forwarding chain. 
   The proposed invention enables precedent callees of the call forwarding chain, especially the first callee where the call actually was destined to, to access the message left by the caller and retrieve the information contained therein. 
   As the first callee is the person who was originally destined to receive the call, the present invention helps to re-establish the intended path of call information distribution even in case of a call forwarding chain. 
   Further advantages are achieved by the embodiments of the invention indicated by the dependent claims. 
   According to a preferred embodiment of the invention, one of the one or more callees specifies a preference with respect to the handling of the call. It is possible that said one callee provides the preference to a multimedia messaging service (=MMS) controlling the automatic call forwarding of said callee. The MMS translates the preference into a corresponding instruction that is to be executed in case of a call forwarding. For example, before activating the call forwarding service, the first callee starts an application (local or central) where the first callee is presented a select list. The first callee selects from the select list a pre-defined preference that best suits his wishes. The callee&#39;s preference selection is stored in a memory as a call forwarding preference associated with the first callee. The selected preference is taken into consideration for the operation of the call forwarding. 
   When the call arrives at the first callee, the callee&#39;s call forwarding is added to the data set appended to the call message. After the call is forwarded to the message memory assigned to a last callee of the call forwarding chain, the data set appended to the call is checked whether it contains a call forwarding preference. The further operation of the call is performed in conformity with the contained call forwarding preference. It is possible that a call forwarding application associated with the last callee analyses call and extracts a call forwarding preference contained within the data set appended to the call message. Then, the call forwarding application follows the instructions corresponding to the call forwarding preference. 
   According to another preferred embodiment of the invention, the first callee&#39;s preference specifies that the message provided by the caller is stored in the message memory assigned to the first callee without being distributed to any of the one or more further callees or to any message memory assigned to the one or more further callees. The callee&#39;s preference data is stored in a memory as a call forwarding preference associated with the first callee. After the call is forwarded to the message memory assigned to said last callee, an indication is made to the caller that instructs the caller to provide a message to be stored in the message memory assigned to the first callee. The address associated with the message memory assigned to the first callee is retrieved from the data set added to the call message. Using the retrieved address as destination address, the message received from the caller is routed to the message memory assigned to the first callee. 
   This embodiment of the invention allows a first callee to access information intended for him without wasting time, even when using a call forwarding service. Let us suppose that the first callee forwards his calls to his colleague because the first callee is in a meeting for some time. The colleague however unexpectedly had to leave the office ahead of schedule. So calls arriving at the colleague&#39;s terminal are call forwarded to the colleague&#39;s mailbox. Since the colleague will not return to the office before the next morning, the first callee would not find out about the left message before the next day. The present embodiment of the invention allows a first callee to define that a call be re-routed to his own mailbox if the call would be forwarded to a mailbox at the end of a call forwarding chain. So the first callee can access his mailbox when he returns from the meeting. 
   According to another preferred embodiment of the invention, a selection procedure for selection of one or more of the one or more callees is executed by then improved call forwarding service, whereby a select list presented in the selection procedure comprises the identifiers of each of the callees involved in the call forwarding chain. This selection procedure may be performed by a call forwarding server associated with the last callee in the call forwarding chain. The caller selects a selection of one or more callees of the one or more callees involved in the call forwarding chain. The caller&#39;s selection is transmitted to a control unit controlling the improved call forwarding service. Based on the received selection, the addresses associated with the message memories assigned to the selected one or more callees are retrieved from the data set. By utilizing the retrieved addresses as destination addresses, it is possible to distribute the message received from the caller to the one or more message memories assigned to the selected one or more callees. 
   The present embodiment allows a caller to choose by himself where to distribute his message. A caller may have the impression that his call does not receive due attention if his call is forwarded and, at the end of the call forwarding chain, his message is stored in a message memory of the last callee. So, the caller is given the opportunity to scatter his message to more than one message memory, and even to choose to which message memories. 
   In a preferred embodiment, a notification is delivered to the one or more of the message memories where the message has not been delivered to. It is possible that this notification indicates that a message has been delivered. It is also possible that the notification indicates further information associated with the course of the call forwarding of the call, e.g., the callees involved in the call forwarding chain, the message memories where the caller&#39;s message has been delivered, etc. This allows a timely distribution of call information to all callees involved in the call forwarding chain, partly by leaving the caller&#39;s message in message memories and partly by leaving a notification about the caller&#39;s message in message memories. 
   According to another preferred embodiment of the invention, the notification may be based on the VPIM or the IMAP (VPIM=Voice Profile for Internet Mail, IMAP=Internet Message Access Protocol). 
   Preferably, all the addresses associated with the message memories are retrieved from the data set. Then, the caller&#39;s message received from the caller is transmitted to all message memories associated with the callees involved in the call forwarding chain by routing the message to all the retrieved addresses. 
   Preferably, the data set is added to the call by encapsulating an Extensible Mark-up Language (=XML) script. This XML script contains a list (e.g., identifiers, names, etc.) of all reached callees, i.e., of the callees involved in the call forwarding chain. Preferably, this XML script also contains an address associated with a respective message memory assigned to each of the callees involved in the call forwarding chain. For example, this address may be an address of the callees&#39; respective Multimedia Messaging Service (=MMS). The XML script may also contain a preference of one or more of the callees. 
   The function of the network entity (=mailbox) receiving the forwarded call message must consider several cases: 
   a) The script is not present in the call message. Then, no further action is to be taken. The function of the mailbox is as today. 
   b) The script is present in the call message. Then, at least one forwarding callee is listed; 
   
       
       
         
           b1) If the mailbox has the capability or is set to propose a selection of destinations for the message, the mailbox proposes to the caller a set of alternatives where to deliver the message (only first callee, first callee and second callee, only second callee, . . . ). 
           b2) The mailbox delivers the caller&#39;s message to all forwarding callees in the list. 
         
       
     
  

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These as well as further features and advantages of the invention will be better appreciated by reading the following detailed description of presently preferred exemplary embodiments taken in conjunction with accompanying drawings of which: 
       FIG. 1  is a block diagram of a call forwarding chain according to an embodiment of the invention. 
       FIG. 2   a  is a message flow diagram according to a first embodiment of the invention. 
       FIG. 2   b  is a message flow diagram according to another embodiment of the invention. 
       FIG. 2   c  is a message flow diagram according to still another embodiment of the invention. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1  shows four subscribers  10 ,  21 ,  22 ,  23  of a wireline and/or wireless telecommunications network, e.g., a PSTN or an ISDN network or a GSM network (PSTN=Public Switched Telephone Network; ISDN=Integrated Services Digital Network; GSM=Global System for Mobile Communication). It is also possible that the telecommunications network is a packet-based network, e.g., the Internet. The four subscribers  10 ,  21 ,  22 ,  23  play the roles of a caller  10  initiating a telephone call, a first callee  21  receiving the caller&#39;s call first, a second callee  22  receiving the caller&#39;s call second, and a third callee  23  receiving the caller&#39;s call third. 
   In the following, when referring to a caller and a callee, it is implied that the caller and the callee each use terminals to send and receive telephone signals without explicitly referring to these terminals. So, the terms “caller/callee” and “terminal associated with/used by a caller/callee” may be used interchangeably. The terminals used by the caller  10  and the callees  21 ,  22 ,  23  may be wireline telephone terminal (POTS telephone set, ISDN terminal) or wireless terminals (DECT telephone set, cellular phone, PDA) (POTS=Plain Old Telephone System; DECT=Digital Enhanced Cordless Telecommunications; PDA=Personal Digital Assistant). It is also possible that the terminals are IP softphones run by a computer application (IP=Internet Protocol). 
   The first callee  21  is connected to a call management system  31  (=mailbox) with a control unit  311  and a software memory  312  and comprising a message memory  210 . The first callee  21  has activated a call forwarding of incoming calls to a second callee  22 . The second callee  22  is connected to a call management system  32  with a control unit  321  and a software memory  322  and comprising a message memory  220 . The second callee  22  has activated a call forwarding of incoming calls to a third callee  23 . The third callee  23  is connected to a call management system  33  with a control unit  331  and a software memory  332  and comprising a message memory  230 . The third callee  23  has activated a call forwarding of incoming calls to his message memory  230 . Thus, the three callees  21 ,  22 ,  23  form a call forwarding chain. 
   Each of the call management systems  32 ,  32 ,  33  is composed of one or several interlinked computers, i.e., a hardware platform, a software platform basing on the hardware platform and several application programs executed by the system platform formed by the software and hardware platform. The functionalities of the call management systems  32 ,  32 ,  33  are provided by the execution of these application programs. The application programs or a selected part of these application programs constitute a computer software product providing a call forwarding service as described in the following, when executed on the system platform. Further, such computer software product is constituted by a storage medium storing these application programs or said selected part of application programs. 
   The call management systems  32 ,  32 ,  33  may be implemented as tangible auxiliary units (physical mailbox) put beside and connected to the terminals of the users  21 ,  22 ,  23 . For example, the call management systems  32 ,  32 ,  33  are mailbox units which are connected to the terminals and which comprise voice recording memories. As the call management systems  32 ,  32 ,  33  are connected to the terminals, they are part of the telecommunications network and represent network units. For example, the call management systems  32 ,  32 ,  33  are represented by a multimedia messaging service (=MMS). 
   It is also possible that the call management systems  32 ,  32 ,  33  are not physically visible to the users  21 ,  22 ,  23  but are “hidden” as call management functions within the network (electronic/network mailbox). For example, the call management systems  32 ,  32 ,  33  are implemented by software applications running on a call management server located in the telecommunications network. 
   The name of the caller  10  may be “Peter”, the name of the first callee  21  may be “Alice”, the name of the second callee  22  may be “Bob”, and the name of the third callee  23  may be “Roger”. 
   Peter  10  initiates a call  400  to Alice  21 . When the call  400  arrives at Alice  21 , the call message of the call  400  is enhanced with an identifier of Alice  21  and her mailbox address. These enhancement data may be added to the call message by encapsulating a XML script into the call message. The XML script may be as follows: 
   
     
       
             
             
           
         
             
                 
                 
             
           
           
             
                 
               &lt;forwardlist&gt; 
             
             
                 
                 &lt;forward&gt; 
             
             
                 
                  &lt;user&gt;alice&lt;/user&gt; 
             
             
                 
                  &lt;messagerie&gt;alicebox&lt;/messagerie&gt; 
             
             
                 
                 &lt;/forward&gt; 
             
             
                 
               &lt;/forwardlist&gt; 
             
             
                 
                 
             
           
        
       
     
   
   The enhanced call is forwarded by the call management system  31  of Alice  21  as a call  401  to Bob  22 . When the call  401  arrives at Bob  22 , the call message of the call  401  is enhanced with an identifier of Bob  22  and his mailbox address. In analogy to the case of Alice  21 , these enhancement data may be added to the call message by encapsulating a XML script into the call message. The entire set of data added to the call as XML script may be as follows: 
   
     
       
             
             
           
         
             
                 
                 
             
           
           
             
                 
               &lt;forwardlist&gt; 
             
             
                 
                 &lt;forward&gt; 
             
             
                 
                  &lt;user&gt;alice&lt;/user&gt; 
             
             
                 
                  &lt;messagerie&gt;alicebox&lt;/messagerie&gt; 
             
             
                 
                 &lt;/forward&gt; 
             
             
                 
                 &lt;forward&gt; 
             
             
                 
                  &lt;user&gt;bob&lt;/user&gt; 
             
             
                 
                  &lt;messagerie&gt;bobbox&lt;/messagerie&gt; 
             
             
                 
                 &lt;/forward&gt; 
             
             
                 
               &lt;/forwardlist&gt; 
             
             
                 
                 
             
           
        
       
     
   
   The enhanced call is forwarded by the call management system  32  of Bob  22  as a call  402  to Roger  23 . When the call  402  arrives at Roger  23 , the call message of the call  402  is enhanced with an identifier of Roger  23  and his mailbox address. The enhanced call is forwarded by the call management system  33  of Roger  23  as a call  403  to Roger&#39;s  23  message memory  230 . 
     FIG. 2   a  shows a message flow diagram of messages exchanged in a telecommunications system to perform a first embodiment of an improved call forwarding. The message flow diagram shown in  FIG. 2   a  involves the caller Peter  10 , the first callee Alice  21 , the second callee Bob  22  and the third callee Roger  23 , as described above with reference to  FIG. 1 . Furthermore,  FIG. 2   a  shows the call management system  31  and the message memory  210  associated with Alice  21 , the call management system  32  and the message memory  220  associated with Bob  22 , and the call management system  33  and the message memory  230  associated with Roger  23 . 
   Peter  10  calls Alice  21  by sending a call message  501  from his terminal to the terminal used by Alice  21 . Alice  21  has activated a call forwarding service on her terminal, so the call  501  is transmitted  502  from the terminal to the associated call management system  31  for further processing. The call management system  31  adds a data set comprising an identifier of Alice  21  and an address of the message memory  210  to the call message and forwards the enhanced message  503  to the terminal used by Bob  22 . 
   Bob  22  has activated a call forwarding service on his terminal, so the call  503  is transmitted  504  from his terminal to the associated call management system  32  for further processing. The call management system  32  adds an identifier of Bob  22  and an address of the message memory  220  to the data set appended to the call message and forwards the enhanced message  505  to the terminal used by Roger  23 . 
   Roger  23  has activated a call forwarding to his mailbox on his terminal, so the call  505  is transmitted  506  from his terminal to the associated call management system  33  for further processing. The call management system  33  adds an identifier of Roger  23  and an address of the message memory  230  to the data set appended to the call message. 
   Possibly, the call management system  33  forwards the enhanced message  507  to the message memory  230  associated with the terminal used by Roger  23 . 
   Upon receipt of the message  506 , the call management system  33  analyses the received message  506  and determines from the added data set that the call  506  is related to a call forwarding chain. The call management system  33  extracts the identifiers contained in the data set, i.e., the identifiers of Alice  21 , Bob  22  and Roger  23 . The call management system  33  further extracts the addresses of the message memories  210 ,  220 ,  230  associated with the identified callees  21 ,  22 ,  23 . Then the call management system  33  sends a message  508  to the caller  10 , i.e., to Peter, to prompt Peter  10  to provide a message to be delivered to the message memories  210 ,  220 ,  230  of the identified callees  21 ,  22 ,  23 . 
   Peter  10  speaks a message in his terminal, and the message is transmitted  509  to the call management system  33  of Roger  23 . The call management system  33  sends  510   a, b, c  the received message of Peter  10  to the message memories  210 ,  220 ,  230  of the identified callees  21 ,  22 ,  23 . This is possible since the call management system  33  has extracted the addresses of the message memories  210 ,  220 ,  230  from the received message  506 . The callees  21 ,  22 ,  23  can access the respective message memories  210 ,  220 ,  230  and listen to the message of Peter  10 . 
     FIG. 2   b  shows a message flow diagram of messages exchanged in a telecommunications system to perform a second embodiment of an improved call forwarding. The message flow diagram involves the same entities as the message flow diagram shown in  FIG. 2   a.    
   The messages  601  to  606  shown in  FIG. 2   b  are identical to the messages  501  to  506  shown in  FIG. 2   a . In addition, however, Alice  21  has provided to the call management system  31  a preference regarding the handling of calls. Alice  21  selects that a call destined to her must not be distributed to message memories associated with other subscribers of the network. Instead, a call destined to her must be sent to her message memory if the call is to be sent to a message memory at the end of a call forwarding chain. This preference provided by Alice  21  is also appended to the data set of the call  602  by the call management system  31 . 
   Upon receipt of the message  606 , the call management system  33  analyses the received message  606  and determines from the added data set that the call  606  is related to a call forwarding chain. The call management system  33  extracts the identifiers contained in the data set, i.e., the identifiers of Alice  21 , Bob  22  and Roger  23 . The call management system  33  further extracts the addresses of the message memories  210 ,  220 ,  230  associated with the identified callees  21 ,  22 ,  23 . 
   The call management system  33  also checks if the received message  606  comprises data concerning a preference of a callee. In the present case, the call management system  33  detects that the message  606  comprises a preference provided by Alice  21 . Accordingly, the call management system  33  does not forward the call to the message memory  230  of Roger  23 . The call management system  33  sends a message  607  to the caller  10 , i.e., to Peter, to prompt Peter  10  to provide a message to be delivered to the message memory  210  of Alice  21 . 
   Peter  10  speaks a message in his terminal. According to a first alternative, the message is transmitted  608  directly to the message memory  210  of Alice  21  (e.g., by means of a re-routing mechanism). According to another alternative, the message is first transmitted  609  to the call management system  33  of Roger  23 . The call management system  33  sends  610  the received message of Peter  10  to the message memory  210  of Alice  21 . This is possible since the call management system  33  has extracted the address of the message memory  210  from the received message  606 . Alice  21  can access her message memory  210  and listen to the message of Peter  10 . 
     FIG. 2   c  shows a message flow diagram of messages exchanged in a telecommunications system to perform a third embodiment of an improved call forwarding. The message flow diagram involves the same entities as the message flow diagram shown in  FIG. 2   a  and  FIG. 2   b.    
   The messages  701  to  706  shown in  FIG. 2   b  are identical to the messages  701  to  706  shown in  FIG. 2   a.    
   Upon receipt of the message  706 , the call management system  33  analyses the received message  606  and determines from the added data set that the call  606  is related to a call forwarding chain. The call management system  33  extracts the identifiers contained in the data set, i.e., the identifiers of Alice  21 , Bob  22  and Roger  23 . The call management system  33  further extracts the addresses of the message memories  210 ,  220 ,  230  associated with the identified callees  21 ,  22 ,  23 . 
   Triggered by the determination that the call  606  is related to a call forwarding chain, the call management system  33  sends a message  707  to the caller  10 . The message  707  comprises a selection procedure which is presented to Peter  10 . For example, a voice message is re-played to Peter  10 , saying: 
   Do you want to leave a message at 
   
       
       
         
           1—Alice 
           2—Bob 
           3—Roger 
           4—Alice &amp; Bob 
           5—Alice &amp; Roger 
           6—Bob &amp; Roger 
           7—all 
         
       
     
  
   Peter  10  may select one entry of the select list by pressing a corresponding number on his terminal or by speaking the corresponding number. Let us assume that he chooses selection 2, i.e., Peter  10  wishes that his message be delivered to Bob  22  only. Peter&#39;s  10  selection is transmitted  708  to the call management system  33 . Accordingly, the call management system  33  generates a prompt such as 
   You may leave a message to Bob. Please speak after the signal. 
   This prompt is provided  709  to Peter  10 . Peter  10  speaks a message in his terminal. The message is transmitted  710  to the call management system  33  of Roger  23 . The call management system  33  sends  711  the received message of Peter  10  to the message memory  220  of Bob  22 . This is possible since the call management system  33  has extracted the address of the message memory  220  from the received message  706 . Bob  22  can access his message memory  220  and listen to the message of Peter  10 . 
   Additionally, it is possible that the caller  10  chooses that a notification is left in the message memories  210 ,  230  where Peter&#39;s  10  message has not been sent. The notification may indicate that a new message has been delivered. Then, the call management system  33  generates a corresponding notification and sends  712   a, b  the generated notification to the message memory  210  of Alice  21  and the message memory  23  of Roger  23 . 
   There may be also an option that the call management system  33  does not request the caller  10  to select a delivery, but that the message is systematically delivered to all message memories  210 ,  220 ,  230  involved in the call, i.e., to the message memories of Alice  21 , Bob  22 , and Roger  23 .