A METHOD AND AN APPARATUS FOR EXCHANGING INFORMATION BETWEEN SUBSCRIBER STATIONS OF A TELEPHONE COMMUNICATION NETWORK

Abstract: In a communication network (N), an information message transfer means (IMTM) handles the independent forwarding of information messages to subscriber stations (A, B). When an initial call set-up request initiated from a first subscriber station (A) fails, this is detected by a detection means (DET). The information message transfer means (IMTM) is then activated and the first subscriber station (A) records a desired information message in a memory (MEM). Then the first subscriber station (A) goes into a "hung-up" operation state and is free for carrying on with other call set-up requests. The recorded information message is then transferred to the second subscriber station (B) by the information message transfer means (IMTM) which sets up an independent call to the desired subscriber station (B). With the independent setting-up of a call, it can be made sure that the information message will eventually reach the second subscriber station (B) without assistance of the first subscriber station (A).

Description: A method and an apparatus for exchanging information between subscriber stations of a telephone communication network The invention relates to a method and an apparatus for exchanging information between subscriber stations of a telephone communication network. Nowadays, communication networks - in particular mobile communication networks with advanced technologies - provide advanced services to their subscriber stations. Calls can be routed and diverted and messages - in particular voice messages or facsimile data - can be left on the called subscriber station, even if the subscriber station does not immediately answer the call, i.e. does not respond when the message is sent. Thus, the requirement that both subscribers are simultaneously present is circumvented by leaving a message on the called subscriber station. However, once the message has been left by the calling subscriber station, there is no further means to verify that the called subscriber station has in one way or other read the message or responded to the message. This problem is mainly caused by the fact that the calling subscriber station is not on-line (i.e. not connected with a line) anymore when the called subscriber eventually decides to read the message. The present invention aims at providing a method and an apparatus for a telephone communication system that allow the exchange of information between subscriber stations such that the stringent requirement that the calling subscriber station must be on-line to verify whether the called subscriber station responds to the transferred message is avoided. The invention is to ensure that in particular a voice message reaches the intended called subscriber station and that the calling subscriber station can get an acknowledgement that the voice message has reached the called subscriber station. Description of the prior art Fig. 1 shows a telephone communication network N for exchanging information between two subscriber stations A, B. The telephone communication network N contains a schematically shown exchange means EX comprising a switching means SW which contains known means for setting up a call between the first and second subscriber station A, B (a call set-up means) and other known means to switch the information in the telephone communication network. Furthermore, the switching means SW also contains known means for queuing a call if e.g. the subscriber station B is in an answer state, i.e. when it communicates with another subscriber station, and has not finished the call as yet. This queuing means queues the call until all preceding calls have been executed. Moreover, the switching means SW can contain an operation state detection means that monitors the operation state of the subscriber stations. For example, the queuing means will queue a call to be set up to the second subscriber station B, when the operation state detection means detects said operation state "answer" for the second subscriber station, but the second subscriber station is still involved in another call. Assuming that the subscriber station A picks up its telephone Tele and sends a call set-up request to the exchange EX, the switching means SW (the call set-up means) will try to set up the call to the telephone Tele of the subscriber station B. However, when the called subscriber station B is busy or when there is no reply from the subscriber station B, then the desired call is unsuccessful. Another situation is when the calling subscriber station A runs out of time or if its desired call set-up request is queued by the queuing means of the switching means SW. If the calling subscriber station A does not have time to wait or to call again later, it can generally - when he is on-line - do nothing else but hanging up and try to transmit information messages in a different form or to do a retry later. Therefore, other facilities are necessary that will allow the calling subscriber station A to leave an information message with the subscriber station B without the requirement that both subscriber stations are simultaneously on-line. Other facilities that allow the leaving of information messages when both subscriber stations are not simultaneously on-line are also shown in fig. 1. The subscriber station A (after being unsuccessful to reach the subscriber station B) might run an E-mail means to send an information message to the E-mail means of the subscriber station B. Apart from the fact that this requires additional equipment in both subscriber stations, there is still no possibility that the subscriber station A receives an acknowledgement that in fact the E-mail information message sent to the subscriber station B has really been read by the subscriber station B. Also the writing of me os requires a separate application. Advanced digital telephone communication networks provide a voice-mail facility that allow to leave a voice information message with the subscriber station B even if it is not on-line simultaneously. Essentially, the voice- mail requires that both subscriber stations have such a voice-mail facility. Furthermore, there is no acknowledgement that the called subscriber station has actually responded to the sent voice-mail. Basically, the voice-mail facilities replaced the conventional answering machines AW which work in an analogous manner, i.e. the calling subscriber station might leave a message on an answering machine. However, still no acknowledgement is sent back until the called subscriber station B calls back the subscriber station A after having read the voice-mail or the information message recorded on the answering machine. There are some further possibilities how interaction can be performed when both subscriber stations A, B are not simultaneously on-line and such facilities are for the sake of simplicity shown to be located within the exchange in fig. 1. The means CCBS is a means that puts the calling subscriber station A on hold, if the operation state detection means detects a busy state of the subscriber station B. It then waits until the operation state of the subscriber station B changes into a on-hook state and then immediately tries to build up the call to the subscriber station B. However, obviously the disadvantage here is that the calling subscriber station A must remain on-line (or switched-on) since otherwise, the call cannot be set up when the subscriber station B eventually hangs up. The means CCBS thus takes care of the "call completion on busy subscriber" . The means CCNR ("call completion on no reply") takes away the burden of redialing from the calling subscriber station A, i.e. if there is no immediate reply from the subscriber station B, the means CCNR will repeatedly call the subscriber station B until it replies. However, the disadvantage here is that of course the subscriber station A must be available or on-line when the subscriber station B eventually answers. The means CW is provided to temporarily interrupt the ongoing call of the called subscriber station B when it is busy to indicate that there is a further call from the subscriber station A that needs to be processed. Obviously, the calling subscriber station A must remain on-line to wait until the subscriber station B decides to hang up due to the indication sent by the means CW during the interruption. Summary of the invention It is easily seen from the above description that on the side of the called subscriber station there are sufficient possibilities that an information message, e.g. a voice message, can be left to be processed by the called subscriber station at an appropriate time. Thus, the information message as such does not get lost even if the called subscriber station does not respond during the sending of the information message. However, on the side of the calling subscriber station, there are no possibilities to make sure that the information message is not only being sent but is also properly responded to. The only thing the calling subscriber station will thus know is that in fact he/she has sent an information message. However, of course it would be desirable if the calling subscriber station could also make sure that a response to this information message takes place. Conventionally, this can only be ensured if the calling subscriber station stays on-line. Therefore, the object of the invention is to provide a method and an apparatus for exchanging information between subscriber stations of a telephone communication network which ensure that information messages are received by a called subscriber station, even when the calling subscriber station and the called subscriber station are not simultaneously on-line during a transfer of the information message . This object is solved by a method according to claim 1 and an apparatus according to claim 20. Essentially, according to the invention, the telephone communication network comprises an independent information message transfer means and the calling subscriber station can select or record an information message in an information message memory means thereof. Then the calling subscriber station may assume a on-hook state (or in fact the calling subscriber station can call a further station or perform any other functions according to need) whilst the information message transfer means will independently build up a separate call to the desired called subscriber station. When the called subscriber station eventually answers, it will transfer the information message to the called subscriber station. Since a separate call is set up between the information message transfer means and the called subscriber station, the information message transfer means makes sure that the called subscriber station really receives the information message. Even though the calling subscriber is not on-line, the task of communicating (e.g. receiving an acknowledgement of receipt of the called subscriber station) has been completely transferred to the information message transfer means. Since the information message transfer means carries out an independent dialogue with the called subscriber station, it can make sure that no information messages are lost and that the called subscriber station properly responds - e.g. by sending an acknowledgement information. For example, the information message transfer means may receive an acknowledgement information and/or an additional reply from the called subscriber station. Subsequently, the information message transfer means can call up the original calling subscriber and transfer such an acknowledgement information back to the calling subscriber station. Advantageously, the information message transfer means can also set up a call between said first and second subscriber station after having transferred the information message to the second subscriber station. For example, when the called subscriber is reached for the message delivery and acknowledgement/reply, then the information message transfer means can always try to reach the calling subscriber as well and if possible set up a connection between the parties (since this was the aim with the original call attempt) . Of course, it is possible to configure this call set-up according to the calling subscriber wishes. The calling subscriber can state already at message recording that he/she wishes to be called back, when the information message transfer means reaches the called subscriber and transfer the message. Thus, the information message transfer means acts on behalf of the calling subscriber station or called subscriber station such that there is no necessity that both subscriber stations are simultaneously on-line in order to make sure that the information messages are properly responded to. Therefore, the information message transfer means acts independently and takes away the burden of redialing from the calling subscriber station. Further advantageous embodiments and improvements of the invention are listed in the dependent claims. Hereinafter, the invention will be explained with reference to its embodiments and the accompanying drawings . Brief description of the drawings The drawings show advantageous embodiments of the invention. Further advantageous embodiments, objects and features will become apparent when considering the drawings together with the description below. Fig. 1 shows a conventional telephone communication network for providing an information exchange between two subscriber stations A, B; Fig. 2 shows a diagram of an information exchange apparatus IEA according to the invention; Fig. 3-1 shows a principle flow chart of the method of the invention with respect to fig. 2; Fig. 3-2 shows the IMTM pre-processing for monitoring a call after the sending of a call set-up request; Fig. 3-3 shows the IMTM processing for sending a message to the called subscriber station; Fig. 3-4 shows a flow chart of the IMTM post-processing with respect to the acknowledgement and a possible dialog with the called subscriber station; Fig. 4 shows an embodiment of the IMTM processing for a "busy state" of the called subscriber station with respect to fig. 3-2; Fig. 5 shows an embodiment of the IMTM processing with respect to a "no-answer" state of the called subscriber station with respect to fig. 3-2; Fig. 6 shows the IMTM processing for an "answer state and queued" of the called subscriber station with respect to fig. 3-2; Fig. 7 shows a flow chart of the acknowledgement processing of fig. 3-4; and Fig. 8 shows an embodiment of a flow chart of the dialog processing of fig. 3-4. In the drawings, identical reference symbols designate the same or equivalent parts or steps. General principle used by the invention Fig. 2 shows a telephone communication network N comprising an information exchange apparatus IEA for exchanging information between subscriber stations A, B according to the invention. The information exchange apparatus comprises a detection means DET for detecting when in response to a call set-up request sent from said first subscriber station A, a call cannot be set up from said first subscriber station A to said second subscriber station B. Such a situation can occur, when the first subscriber station A sends a call set-up request and the second subscriber station B has an operating state "busy" or has an operation state "no answer", i.e. when the second subscriber station simply does not answer the call. An information message transfer means IMTM comprises a transmission/reception means TR, an information message memory means MEM and a call set-up means SET. The information message memory means MEM stores at least one transfer information message which can be pre-recorded or set by said first subscriber station A as will be explained below. The call set-up means SET can set up a call to the subscriber station A and/or the subscriber station B. That is, the call set-up means SET can establish a connection independently with one of the subscriber stations A, B. The call set-up means can also establish a connection between A and B after an information message has been transferred as will also be further explained below. The call set-up means SET may use the switching facilities of the switch SW for building up the call. When a call to one of the subscriber stations A, B has been set up from IMTM, the transmission/reception means TR can send one of the transfer information messages from the information message memory means MEM to the subscriber stations A or B. An activation means AC is provided for activating the information message transfer means IMTM when the detection means DET detects that a direct call between the subscriber stations A, B cannot be built up. Since the information exchange apparatus shown in fig. 2 can independently establish a dialog with one of the subscriber stations A, B for transferring a pre-recorded information message, this takes away the burden or redialing or waiting in a on-line situation by the subscriber stations A, B when the call between the first and second subscriber stations A, B cannot be set up directly. Whilst the subscriber stations A, B may have the additional E-mail, Voice-mail etc. facilities as shown in fig. 1, these are not invariably necessary in fig. 2, since the information message transfer means IMTM will take over the forwarding of information messages. Thus, the information exchange apparatus acts as a "further intelligent subscriber" to make sure that information messages after having been recorded by the calling subscriber station reach the called subscriber station. If after several attempts B still does not answer, the apparatus can send messages to A as well as to B to act as an independent intermediator. Fig. 3-1 shows a principle flow chart of the processing carried out by the information exchange apparatus IEA in fig. 2. Basically, three stages of an IMTM pre-processing in step S2, an IMTM processing in step S3 and an IMTM post-processing in step S4 can be distinguished. That is, in step Sll, a subscriber station A decides to send a call set-up request to the subscriber station B. The switch means SW or the detection means DET respectively detects whether this call to the subscriber station B can actually be established. The detection means DET can for this purpose comprise a first, second or third monitoring means which directly monitor an operation state of the second subscriber station B in step S12 after the call set-up request has been sent in step Sll. These monitoring means can e.g. detect a "busy" state, a "no-answer" state, a "no direct answer" state and a "direct answer" state of said called subscriber station B. According to the IMTM pre-processing in step S2, the IMTM processing in step S3 then decides whether a call to the subscriber station B can directly be set up or whether an independent forwarding of information messages needs to be done. In step S4, an IMTM post-processing is performed dependent on the IMTM processing in step S3. If a direct call can be established in step S2 and step S3, then there is no necessity for an IMTM post-processing step S4. If there was no direct answer to the call set-up request and a message has been transferred in step S3, the IMTM post- processing in step S4 takes care of the forwarding of an acknowledgement/information message transfer to the calling subscriber station A. For example, the called subscriber station B can in response to a call set-up acknowledgement request from the information message transfer means IMTM directly leave a message with IMTM which is then transferred to the calling subscriber station A. Fig. 3-2 shows the IMTM pre-processing with respect to the monitoring of the different operation states of the called subscriber station B by the detection means DET (by the first, second and third monitoring means) with more details. As in fig. 3-1, the call set-up request is sent from the subscriber station A in step Sll. In step S121, the monitoring means monitors the operation state of the called subscriber station B, i.e. the detection means monitors the reaction of the called subscriber station B to the call set-up request. In step S121, three possibilities can be in principle distinguished: a) "busy state": called subscriber station is talking to another subscriber station; b) "no answer state": the called subscriber station B does not answer at all, i.e. is in an "on-hook" state; c) "answer state": the subscriber station B in principle reacts to the call set-up request. As is seen with step S122, the "answer state" in a modern telecommunication network can still lead to either a "direct answer" and a normal immediate call establishment between A and B in step S124 (when no queue is present) or the call is answered and put into a queue in step S123. The telephone communication network N comprises a queuing means for putting the call in a waiting queue in step S123 for execution. A third monitoring means of the detection means DET then monitors the waiting queue until the queued call A is ready for execution in the waiting queue. As seen from fig. 3-2, there are in principle three different conditions that may lead to the IMTM processing in step S3, namely a "busy state", a "no answer state" or a "queue state" of the called subscriber station B. Although the IMTM processing in step S3 is dependent in principle on the specific condition a) , b) , c) , the basic processing for the IMTM processing is common to all three conditions as is shown in fig. 3-3. In all three conditions shown in fig. 3-2, the information message transfer means IMTM is activated in step S31. This can be done by the first subscriber station or automatically by the detection means DET in response to detecting one of the three aforementioned conditions. When the information message transfer means IMTM has been activated in step S31, a message to be sent to the subscriber station B is determined in the information message memory means MEM in step S32. In fact, in step S32 a default message can be determined which can always be sent to the subscriber station B if the direct call between A, B cannot be set up due to the occurrence of the conditions a), b) , c) discussed above. Another possibility is that one of several information messages in the information message memory means MEM is selected automatically, e.g. in response to the type of called subscriber station B or in response to the dialed local area code or distance area code. The selection of an information message may also be time-dependent, i.e. if the subscriber station A has already made a number of retries to directly contact the subscriber station B before activating the information message transfer means IMTM, then a different information message will be selected by contrast to a case where the activation was done immediately after the first attempt. The information message transfer means IMTM may also prompt the subscriber station A to record a desired information message in the information message memory means MEM. Such information messages can e.g. be simple information messages like "subscriber station A tried to call on day.month. year at xx.xx hours", "subscriber station A tried to call, please call back the following number" or "subscriber station A called, please call back tomorrow". However, the information message can also indicate more complex operations, e.g. "subscriber station A called and wants to be called back after information message transfer; IMTM will now reconnect you to subscriber station A" . When such a message has been sent to and received by subscriber station B and B remains on-line, the IMTM will set up a call between B and A if station A is not in a busy state. If it is in a busy state or any other state that does not allow an immediate answering of the call, B can leave a message whereafter IMTM tries to call A later in a similar manner as was done before when A called first. The information message can - as explained - also be time- dependent, i.e. when IMTM has successively tried to build up a call between IMTM and the subscriber station B, then a message could read as follows: "subscriber station A called; IMTM has tried to call you x number of times". In step S33, the call set-up means tries to set up a call to the subscriber station B. For doing so, the set-up facilities of the switching means SW can be used directly. Alternatively, the information message transfer means may incorporate a call set-up means SET as is shown in fig. 2. At this time, the subscriber station A is fully independent for other operations, since the information message transfer means IMTM now takes over the transfer of the desired message to the subscriber station B. Therefore, in step S33, if the subscriber station B is still in a "busy" state or a "no-answer" state, the information message transfer means IMTM can use all the normal call establishment procedures conventionally provided in a communication network. That is, the information message transfer means IMTM can repetitively call the subscriber station B (possibly with a transfer of different information messages according to the number of re-tries) . However, the burden is taken away from the subscriber station A. Eventually, the information message is sent in step S34 when the subscriber station B finally answers the call from the information message transfer means IMTM. Then the program returns in step S35. Therefore, as is obvious from fig. 3-3 according to the invention, an independent service is provided, which delivers an information message to a called subscriber station, even though the calling subscriber station is no longer participating in the call. That is, the information message transfer means IMTM behaves as if it was the subscriber station A and takes over all the tedious redialing tasks which otherwise would have to be carried out by the subscriber station A. Eventually, the subscriber station B will answer the call from the information message transfer means IMTM so that it can be ensured that the information message will have been read by the subscriber station B. As explained above as a result of various conditions during the IMTM pre-processing in step S2, the subscriber station A communicates with the information message transfer means IMTM in steps S31, S32, namely to determine and record a desired information message in the information message memory means MEM. For example, the reason for activating the IMTM is possibly a result of the fact that the subscriber station B was in a "busy state" or "queue state" during the initial call-setup request from the subscriber station A. Since the information message transfer means IMTM always monitors the operation state of the subscriber station B, even when it communicates with the subscriber station A for recording a message, it may happen that the subscriber station B suddenly goes into an "on-hook state" from the "busy state" or from the "queue state" into the "answer state". This means that actually during a message recording by the subscriber station A (which still communicates with IMTM) suddenly the subscriber station B changes into an operation state that allows an immediate call setup to subscriber station B. Therefore, according to another embodiment of the invention, the information message transfer means IMTM sets up the (initially requested) call between the subscriber station A and the subscriber station B if IMTM recognizes that the subscriber station B changes its operation state from "busy" into "on-hook" or from "queue state" into "answer state" whilst it is still communicating with the subscriber station A for recording the message. That is, IMTM will exit the IMTM processing in steps S31, S32 after it has directly set up the call between the subscriber station A and the subscriber station B. Fig. 3-4 shows the principle of the IMTM post-processing in step S4 after the IMTM main processing in step S3. Again, the IMTM post-processing may be dependent on what actually happened in the IMTM processing, however, in principle an acknowledgement reply may be received from B and a subsequent dialog between IMTM and A or even between B and A can be set up in steps S41, S42, respectively. That is, the information message transfer means IMTM cannot only set up calls to the intended called subscriber station B, but also to the subscriber station A which originally tried to establish a call to subscriber station B. Therefore, when the information message transfer means IMTM has eventually established a call between IMTM and the subscriber station B and an information message has then been transferred in step S34, the information message transfer means IMTM can then also call up the subscriber station A in order to transfer an acknowledgement information that the information message has in fact been transferred. This message will indicate to the subscriber station A that the message was not recorded in vain, but has actually arrived at the subscriber station B. Whilst in the simplest case the acknowledgement information might just be "IMTM has transferred your information message to the subscriber station B", i.e. the acknowledgement information was generated by the information message transfer means IMTM itself, of course the subscriber station B can send back an acknowledgement information to the IMTM during a time when the call is still established between IMTM and the subscriber station B after the information message transfer. The acknowledgement information may contain a personal message from the subscriber station B in response to the information message transferred by the information message transfer means IMTM. That is, together with the acknowledgement information, there can also be a recorded reply (in the memory MEM) from the called subscriber station B, e.g. "Dear A, I have read your information message dated ... today. I will call you back on ...". It will be appreciated that such an information message will likewise be set by default or may be recorded by the subscriber station B when communicating with the IMTM. Thus, what was said above for the information message selection by the subscriber station A likewise is true for the selection of an information message by the subscriber station B when it wants to leave a special acknowledgement message. This can be done automatically or set by the subscriber stations. Furthermore, it will be appreciated that all information messages can be a text message or a voice message. Further details and embodiments of fig. 3-3 and fig. 3-4 will further below be discussed with reference to fig. 4 to 6 and fig. 7, 8, respectively. As was described above, the information exchange apparatus according to the invention takes over an independent exchange of information to a subscriber station which does not immediately respond during a call set-up, thus decreasing the burden on the calling subscriber station for redialing, whilst it can be simultaneously ensured that the information message is transferred and received by the called subscriber station. Since the information message transfer means IMTM can independently communicate with the subscriber stations A, B, the information message transfer means IMTM can - after receiving an acknowledgement information from the subscriber station B to be transferred to A - use the same procedure as was explained for the initial calling of the subscriber station B. That is, when the information message transfer means IMTM desires the transfer of the acknowledgement information to the subscriber station A in response to the subscriber station B having answered, then the IMTM may repeatedly try to set up a call to the subscriber station A if the subscriber station A happened to be in a "busy" state or a "no-answer" state. As was explained above, after step S34, the calling subscriber station A is not participating in the call between IMTM and the subscriber station B. However, as a further embodiment of the invention, the information message transfer means IMTM can build up a call between the subscriber station B and the subscriber station A when in fact the subscriber station B answers the call from the IMTM. That is, automatically IMTM will establish a call between B and A by sending a call set-up request to the subscriber station A. The information message before this call establishment would be "subscriber station A called; IMTM will now try to reconnect you to subscriber station A". If in this case the subscriber station A is a "busy state", then the subscriber station B may select and transfer information messages just as the subscriber station A did when initially the subscriber station B did not answer. Therefore, if the information message transfer means IMTM fails to build up the call between B and A after the information message transfer and with the subscriber station B now being "on-line", then the procedures in fig. 3-2, 3-3, 3-4 may be carried out for the subscriber station B. In fact, steps S32, S33, S34 may be replaced by a direct call set-up procedure to immediately try to build up a call to the subscriber station A once the call between IMTM and the subscriber station B has been established. Furthermore, it should be noted that all routing and diversion means of an advanced telecommunication network can be used to transfer the information messages to the respective subscriber stations. Therefore, when originally during a call set-up request sent from the information message transfer means IMTM the subscriber station B has moved to a different location, then the call set-up request and the information message, respectively, will be routed to the new location of the subscriber station B. Hereinafter, some specific embodiments of the inventive method and the apparatus are described for the three conditions, namely "busy state", "no-answer state" and "queuing state" with reference to fig. 3-2 and fig. 4 to 6. a) Called subscriber station is in a "busy state" Fig. 4 shows a flow chart when a busy state of said second subscriber station B occurs during the initial call set-up request from A in steps Sll, S21. In step Sll, the subscriber station A sends a call set-up request to B . In step S121, a first monitoring means of the detection means DET monitors an operation state of said second subscriber station B and determines that B is a "busy state". In step S31, the subscriber station A itself activates the IMTM and in step S321, a recording means of the information message transfer means IMTM is used for recording a message in the information message memory means MEM. Then the subscriber station A hangs up in step S322 and the first monitoring means continuously monitors the operation state of B in steps S331, S332 in order to set up a call to B in step S33 shown in fig. 3-3. When eventually in step S332, the subscriber station B has changed from a "busy state" into a "hung-up state", the call set-up means SET will establish a call between IMTM and B in step S333. Then the desired message is sent in step S34 to the subscriber station B. In step S4, an appropriate IMTM post-processing is performed with respect to possible transfer of acknowledgement/reply messages or dialogs with A as will be explained below with reference to fig. 7, 8. Fig. 7 shows an embodiment of the acknowledgement processing in step S41 shown in fig. 3-4. First, in step S411, IMTM determines whether the subscriber station B has voluntarily or automatically already sent an acknowledgement/reply message. When B sends this message, it is received by IMTM in step S413. When B does not send a message in step S411, the IMTM requests an acknowledgement information and/or a reply from the subscriber station B in step S412. When in step S413, the subscriber station B after the call establishment and sending of the message sends back its acknowledgement information and/or reply message, the processing returns in step S414. Thus, the processing in fig. 7 can ensure that an acknowledgement message/reply is received by the IMTM. Fig. 8 shows the processing in step S42 with respect to a setting-up of a dialog between IMTM and A or between B and A after the receiving of an acknowledgement/reply message. However, it should be noted that step S41 can also be skipped, i.e. immediately after a successful delivery of the information message to the subscriber station B, the IMTM can transfer a default message to the subscriber station A which is preset to indicate that the transfer of the message to B was successful. Thus, in step S421 in fig. 7, the IMTM will call the subscriber station A. After a call set-up to A in step S421 is performed by the call set-up means SET, the IMTM transfers the acknowledgement information and/or reply to the subscriber station A in step S422. In step S421, several re-tries can be performed according to a predetermined time schedule until the subscriber station A answers. If it does not answer at all, the subscriber station B can be called again to transfer a corresponding message to B that the subscriber station A has not received the desired acknowledgement information and/or the reply information from the subscriber station B. It will be appreciated that in an analogous manner all set-up procedures shown in fig. 3-1, fig. 3-2, fig. 3-3, fig. 4 to 7 can now be used for setting up a corresponding call between IMTM and A. After the acknowledgement/reply message has been transferred to A in step S422, it may be determined in step S423, whether a direct call between A <- B should be established. If so, a direct call between A <- B is set up in step S424, whereafter a normal call processing between A and B takes place in step S425. When it is not desired to establish a call between A and B in step S423, the IMTM post-processing comes to an end in step S5. As already mentioned above, it is not absolutely necessary to carry out step S41 in fig. 3-4 and thus step S422 in fig. 8. That is, if the called subscriber station B is reached for the message delivery in step S333 and S34, then the information message transfer means IMTM can try to reach the calling subscriber station A as well and if possible set up a connection between the subscriber stations B and A (since this was the aim with the original call attempt) . Of course, as already discussed above, the calling subscriber station A can already record an information message in step S32, S321 indicating that A wants to be called back immediately after the information message transfer. Therefore, according to the configuration of the calling subscriber station A by leaving a specific information message, it will be determined in step S423 that a call between A and B is desired after the information message transfer in step S34 or after the additional optional acknowledgement/reply message transfer in step S422. In principle, IMTM may even decide to establish a call directly between B and A, once B has hung up in step S332, namely immediately after the subscriber station B has finished other calls. As explained, this can also be done after the message has been sent in step S34, after the acknowledgement and/or reply information has been received in step S413 or after the acknowledgement and/or reply information has been transferred to the subscriber station A in step S422. b) Subscriber station B is in a "no-answer state" Fig. 5 shows an information message transfer when B is detected to be in the "no-answer" state, i.e. when it is not busy but does not answer the call. When a second monitoring means of said detection means DET detects a no- answer state in step S121 after the set-up request in step Sll, the first subscriber station A activates the IMTM in step S31 and records a message in the memory MEM in step S321. In step S322, the subscriber station A goes into a "hang-up" state. The IMTM tries to establish a call between IMTM and B in step S334. In step S355, the second monitoring means of the detection means DET still detects a "no-answer state", so that a time schedule for recalling is set in S336. Then the IMTM performs a number of retries going through the loop S334, S335, S336 using the predetermined time schedule for recalling until the subscriber station B answers the call ("N" in step S335) . Then the steps S333, S34, S4 as in fig. 4, fig. 3-4 and fig. 7, 8 may be carried out, i.e. the sending of the message and optionally the receiving and sending of the acknowledgement information and the reply. Thus, from step S333, the procedure is the same as in fig. 4. As was explained above, the predetermined time schedule may be set by the IMTM automatically or may be set by said first subscriber station. Furthermore, the information message may be amended according to the number of re-tries in the loop, e.g. that it contains an indication as to the number of re-tries. c) Call queuing In fig. 6, it is decided by a third monitoring means of said information message transfer means in step S122 whether the call to subscriber station B is queued, i.e. whether B is basically in an "answer state", but cannot answer immediately due to the queuing. After it has been detected in step S122 that a call cannot be set up ("Y" in step S122) , the call is put in a queue in step S123 and the subscriber station A activates IMTM and records a message in steps S321, S322, after which A hangs up in step S322. Thereafter, in step S337, the third monitoring means monitors whether the call has passed the queue, i.e. whether the call has reached a position for execution in the waiting queue. When the third monitoring means detects that the call is ready for execution in step S338, ("N" in step S338), the procedure is the same as the steps S333, S34 and S4 in fig. 5. Since at this time, the subscriber station A is in a "hang-up state", the call that was originally requested by the subscriber station A and was then queued in step S123 is therefore used by the information message transfer means IMTM for transferring the recorded message. Therefore, when the queued call reaches the execution stage, then it is not the subscriber station A that uses this call, but instead the information message transfer means for transferring the recorded message. In this embodiment the third monitoring means of the information message transfer means detects that the call is no longer in the queue and that the call has been set up to the subscriber station B. Again, after the message transfer has been completed with the queued call, IMTM may immediately set up a call between B and A, if A can be reached through a call setup. This can be performed with our without additional message transfer and/or repetitive re-tries and/or queuing as in step S33 respectively shown in fig. 4, 5, 6. d) Unsuccessful delivery of a message In each of the above-described embodiments in fig. 3 to 6, the information message transfer means can call up the subscriber station A if it was unsuccessful in delivering the originally requested message or if the called subscriber station B does not leave any acknowledgement. That is, if the IMTM is unsuccessful to transfer the message in steps S33, S34 in fig. 3-3, never detects a hung-up state in step S332 in fig. 4, never detects an answer state in S335 in fig. 5 or never detects that the queued call has reached an execution stage in step S338 (or the call cannot be set up after step S338), then the IMTM will call up the subscriber station A to deliver an automatically set information message indicating that the desired information message transfer was unsuccessful. As already explained above, the information message transfer means IMTM can also decide to immediately perform a "call completion to busy subscriber" when the called subscriber station goes "on hook" (steps S423, S424, S425 in fig. 8) . That is, immediately after the subscriber station B (after a "busy state") has "hung up", the information message transfer means IMTM will try to build up a call between the subscriber station B and the subscriber station A. If then the subscriber station A fails to respond, IMTM will proceed to select an information message and perform a number of re-tries just as was done to call up the subscriber station B after an initial call set-up request from the subscriber station A. As explained above, the information exchange apparatus according to invention forwards messages and builds up calls to subscriber stations even if the calling subscriber station is already "on hook" again (and busy with calling another subscriber) and if the called subscriber station cannot immediately respond to the call initiated by the subscriber station A. Thus, the information exchange apparatus according to the invention can independently from the calling subscriber station carry out a waiting and hunting procedure of the desired called subscriber station, thus reducing the burden on the calling subscriber station to make sure that messages are eventually transferred to the called subscriber station. Since the information message is one way or other always transferred to the called subscriber station, the calling subscriber station can rely on the fact that the called subscriber station has at least once noted this information message. If an acknowledgement information is being sent back (by the information message transfer means calling up the calling subscriber station A) , the calling subscriber station may receive a reply message and/or an acknowledgement information indicating that the called subscriber station B has indeed reacted to the originally transferred information message. Thus, the inventive apparatus and the method will enable a higher call completion and thus more traffic in the telephone communication network whilst at the same time reducing the recalling burdens on the subscriber stations. Whilst conventionally only passive answering machines or voice-mail facilities were available, the apparatus and the method of the invention may be seen as an active "calling machine" that hunts after called subscriber stations which during the initial call set-up could not answer. Furthermore, the calling subscriber station can be provided with an acknowledgement that the message has indeed been transferred and whether the called subscriber station has actually responded to it. References numerals in the claims only serve illustration purposes and do not limit the scope of the claims.

Claims: Claims 1. A method for exchanging information between subscriber stations (A, B) of a telephone communication network (N) , comprising the following steps : aO) detecting (S2, S12) whether during a call set-up request (S2, Sll) a call can be set up from a first subscriber station (A) to a second subscriber station (B) ; al) activating (S3, S31) an information message transfer means (IMTM) when it is detected that a call from said first subscriber station (A) to said second subscriber station (B) cannot be set up (S121, S122); a2) determining (S3, S32) an information message to be transferred to said second subscriber station (B) ; a3) setting up a call (S3, S33) between said information message transfer means (IMTM) and said second subscriber station (B) ; and a4) transferring (S3, S34) said information message from said information message transfer means (IMTM) to said second subscriber station (B) . 2. Method according to claim 1, characterized in that an operation state of said second subscriber station (B) is monitored (S2, S121) and it is detected in said step aO) that a call to said second subscriber station (B) cannot be set up, when said monitored operation state indicates a busy state of said second subscriber station (B) ; and in said step a3) , said information message transfer means (IMTM) sets up (S3, S33, S333) said call between said information message transfer means (IMTM) and said second subscriber station (B) , when said monitored operation state (S331) has changed from a busy state into a hang-up state (S332) . 3. Method according to claim 1, characterized in that an operation state of said second subscriber station is monitored (S2, S121) and it is detected in said step aO) that a call to said second subscriber station (B) cannot be set up, when said monitored operation state indicates a no-answer state (S121) of said second subscriber station (B) , wherein in said step a3) , said information message transfer means (IMTM) repeatedly sends (S3, S33, S334-S336) a call set-up request to said second subscriber station (B) and sets up a call between said information message transfer means and said second subscriber station after an operation state of said second subscriber changes into an off-hook state (S335) . 4. Method according to claim 3, characterized in that said sending (S33) of said repetitive call set-up request is performed according to a predetermined time schedule (S336) . 5. Method according to claim 4, characterized in that said predetermined time schedule is set by said first subscriber station (A) . 6. Method according to claim 1, characterized in that an operation state of said second subscriber station (B) is monitored (S2, S121, S122) and it is detected in said step aO) that a call to said second subscriber station (B) cannot be set up, when said monitored operation state indicates an answer-state of said second subscriber station (B) and said second subscriber does not directly answers, whereafter said call is put (S123) in a waiting queue for execution; and in said step a3) , said information message transfer means (IMTM) monitors said waiting queue (S337, S338) and sets up a call (S333) between said information message transfer means (IMTM) and said second subscriber station (B) at a time when said queued call assumes a position for execution in said waiting queue (S338) . 7. Method according to claim 1, characterized in that after step a4) , said information message transfer means (IMTM) transfers (S412) a request for an acknowledgement information to said second subscriber station (B) . 8. Method according to claim 1 or 7, characterized in that said second subscriber station transfers back (S413) an acknowledgement information to said information message transfer means (IMTM) after receiving said transferred information message (S34) . 9. Method according to claim 8, characterized in that said information message transfer means (IMTM), in response to receiving said acknowledgement information from said second subscriber station (B) , sets up a call (S42, S421) between said information message transfer means and said first subscriber station (A) and transfers (S422) said acknowledgement information to said first subscriber station (A) . 10. Method according one or more of claims 7 to 9, characterized in that said acknowledgement information comprises an acknowledgement message indicating a successful receipt of said transferred information message at said second subscriber station and/or a reply message from said second subscriber station. 11. Method according claim 9, characterized in that said steps aO) to a4) are analogously carried out (S421; Fig. 8) to transfer said acknowledgement information to said first subscriber station, when it is detected that a call cannot be set up to said first subscriber station. 12. Method according to claim 1 or 7, characterized in that said information message transfer means sets up a call (S421) between said information message transfer means (IMTM) and said first subscriber station (A) and transfers an information message to said first subscriber station (A) which indicates that the transfer of said information message to said second subscriber station was unsuccessful, if no acknowledgement is received from said second subscriber station. 13. Method according to one or more of the preceding claims, characterized in that said activation (S31) of said information message transfer means in said step al) is done automatically or by said first subscriber station (A) , when it is detected that a call cannot be set up between said first and second subscriber station. 14. Method according to claim 1, characterized in that routing and diversion means are used at said second subscriber station to transfer said information message to said second subscriber station. 15. Method according to claim 1 or 3, characterized in that a content of said information message changes according to the time needed for setting up the call between said information message transfer means (IMTM) and said second subscriber station (B) in step a3) . 16. Method according to claim 1 , characterized in that said information message transfer means (IMTM) has stored (MEM) therein a number of information messages which are predefined. 17. Method according to claim 1, characterized in that said first subscriber station (A) records one or a number of information messages in said information message transfer means (IMTM) after step al) and one of them or a plurality of them are determined in step a2) . 18. Method according to claim 1, characterized in that after said step a4) said information message transfer means (IMTM) sets up a call (S432, S424, S425) between said first and second subscriber station (A, B) . 19. Method according to claim 18 and 9, characterized in that said call between said first and second subscriber station (A, B) is set up, when said acknowledgement information and/or said information message indicates that the first subscriber station wants to be called back after a successful information message transfer. 20. Information exchange apparatus (IEA) for exchanging information between subscriber stations (A, B) of a telephone communication network (N) , comprising the following features: aO) a detection means (DET) for detecting (S2, S12) when in response to a call set-up request (S2, Sll) sent from said first subscriber station (A) a call cannot be set up from said first subscriber station (A) to said second subscriber station (B) ; al) an activation means (AC) for activating (S3, S31) an information message transfer means (IMTM) when said detection means detects that a call cannot be set up (S121, S122); al) said information message transfer means (IMTM) transferring information messages to said second subscriber station in response to said activation and including: all) an information message memory means (MEM) for storing at least one transfer information message; al2) a call set-up means (SET) for setting up a call to one or both of said subscriber stations in response to said activation; and al3) a transmission/reception means (TR) for sending one of said transfer information messages from said information message memory means to said second subscriber when a call has been set up between said information message transfer means and said second subscriber. 21. Apparatus according to claim 20, characterized by- said detection means (DET) comprising a first monitoring means for monitoring an operation state of said second subscriber station, wherein said detection means (DET) detects that a call to said second subscriber station cannot be set up, when said monitored operation state indicates a busy state of said second subscriber station; and said call set-up means (SET) setting up (S3, S33, S333) a call between said information message transfer means (IMTM) and said second subscriber station (B) , when said monitoring means detects that the operation state has changed from a busy state into a hang-up state (S332) . 22. Apparatus according to claim 20, characterized by said detection means (DET) comprising second monitoring means for monitoring an operation state of said second subscriber station (B) , wherein said detection means (DET) detects that a call to said second subscriber station (B) cannot be set up, when said monitored operation state indicates a no-answer state of said second subscriber station (B) ; and said call set-up means (SET) repeatedly sending (S3, S33, S334-S336) a call set-up request to said second subscriber station and setting up a call between said information message transfer means (IMTM) and said second subscriber station after an operation state of said second subscriber station changes into an off- hook state (S335) . 23. Apparatus according to claim 22, characterized by said call set-up means (SET) sending said repetitive requests for a call set-up according to a predetermined time schedule. 24. Apparatus according to claim 23, characterized in that said predetermined time schedule is set by said first subscriber station. 25. Apparatus according to claim 20, characterized in that said telephone communication network (N) comprises a queuing means for putting (S123) said call in a waiting queue for execution when said detection means detects that said monitored operation state indicates an answer state of said second subscriber and said second subscriber does not directly answers (S2, S121, S122) ; and said information message transfer means (IMTM) comprises a third monitoring means for monitoring (S337, S338) said waiting queue, wherein said call set-up means sets up a call (S333) to said second subscriber station at a time, when said third monitoring means detects that said queued call assumes a position for execution in said waiting queue (S338) . 26. Apparatus according to claim 20, characterized in that said transmission/reception means (TR) transfers (S412) a request for an acknowledgement information to said second subscriber station. 27. Apparatus according to claim 20 or 26, characterized in that said second subscriber station (B) transfers back an acknowledgement information to said transmission/reception means after receiving said transferred information message (S34) . 28. Apparatus according to claim 27, characterized in that said transmission/reception means (TR) , in response to receiving said acknowledgement information from said second subscriber station, activates said call set-up means (SET) to set up a call to said first subscriber station (A) , wherein said transmission/reception means (TR) transfers said acknowledgement information to said first subscriber station. 29. Apparatus according to one or more of claims 26 to 28, characterized in that said acknowledgement information comprises a acknowledgement indicating a successful receipt of said transferred information message at said second subscriber station and/or a reply message from said second subscriber station. 30. Apparatus according to claim 28, characterized in that when said detection means (DET) further detects that said call cannot be set up to said first subscriber station, said information message transfer means (IMTM) transfers (S421; Fig. 8) an information message according to features all)-al3). 31. Apparatus according to claims 20 or 26, characterized in that if said second subscriber station (B) does not send back an acknowledgement information, said call set-up means (SET) sets up a call between said information message transfer means and said first subscriber station and transfers an information message to said first subscriber station (A) which indicates that the transfer of said information message to said second subscriber station (B) was unsuccessful. 32. Apparatus according to one or more of the preceding claims, characterized in that said activation of said information message transfer means by said activation means (AC) is done automatically or via a command issued by said first subscriber station (A) , when said call cannot be set up between said first and second subscriber station. 33. Apparatus according to claim 20, characterized in that routing and diversion means are provided to transfer said transfer information message to said second subscriber station. 34. Apparatus according to claim 20 or 22, characterized in that a content of said information message changes according to the time needed for setting up the call between said information message transfer means and said second subscriber station. 35. Apparatus according to claim 20, characterized in that said information message transfer means (IMTM) comprises a recording means for recording an information message input by said first subscriber, when said call between said first and second subscriber station cannot be set up. 36. Apparatus according to claim 20, characterized in that after said information message has been transferred said information message transfer means (IMTM) sets up a call (S432, S424, S425) between said first and second subscriber station (A, B) . 37. Apparatus according to claim 36 and 29, characterized in that said call set-up means (SET) sets up said call between said first and second subscriber station (A, B) , when said acknowledgement information and/or said information message indicates that the first subscriber station wants to be called back after a successful information message transfer. 38. Method according to claim 1, characterized in that an operation state of said second subscriber station (B) is monitored continuously in steps al) , a2) and a call is set up between said first subscriber station (A) and said second subscriber station (B) when it is detected in said steps al) , a2) a change of operation state of said second subscriber station (B) from a busy state into a hang-up state or from a queue state into an answer state is detected. 39. Information exchange apparatus (IEA) according to claim 2, characterized in that said detection means also detects an operation state of said second subscriber station (B) when said activation means (AC) has activated said information message transfer means (IMTM) or when a message is recorded in said information message memory means (MEM) by said first subscriber station (A) and a call is set up by said information message transfer means (IMTM) when said detection means (DET) detects a change of operation state of said second subscriber station (B) from a busy state into a hang up state or from a queue state to an answer state.

Inventors: BERN MATS, BERN SARA, BERN, MATS, BERN, SARA
Applicants: ERICSSON TELEFON AB L M, TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
Application year: 1998
Main classification: H04M3
IPC codes: H04M3, H04Q7