WO2000049831A1

WO2000049831A1 - Device and method for decentralized realization of complex service features

Info

Publication number: WO2000049831A1
Application number: PCT/DE2000/000271
Authority: WO
Inventors: Wilhelm Westendorf
Original assignee: Siemens Aktiengesellschaft
Priority date: 1999-02-16
Filing date: 2000-02-01
Publication date: 2000-08-24
Also published as: DE19906385A1

Abstract

The invention relates to a device and a method for decentralized realization of the complex service features in a digital network (N, P). According to the invention, selected service features ( call-back, pick-up facility) are encoded in an information element that is transparently transmitted by the digital network (N, P) and are transmitted to a terminal (A - D). Said information element is evaluated and a corresponding service feature is produced in the respective terminal (A - D). The invention facilitates the production of complex service features in a decentralized manner and at low costs without any influence on the network (N, P).

Description

description

Device and method for the decentralized implementation of complex service features

The present invention relates to a device and a method for the decentralized implementation of complex service features of digital terminals in a network and in particular to the simulation of complex service features using the D-channel signaling of layer 3 of the Euro-ISDN protocol DSS1 in a digital Network.

Complex service features are usually known from private switching systems (e.g. HICOM)

To improve user comfort, certain service features can be implemented in a respective subscriber terminal. Such service features are, for example, a "call pickup" or a "callback".

The "call pickup" service feature enables, for example, an incoming call to be taken over by another subscriber terminal during the call phase, without so-called brokering or queries being necessary. Such service features have so far only been possible centrally in private branch exchange systems with system-bound telephones or subscriber terminals. As a result, an incoming call is usually sent by the private branch exchange as a message in a display unit of all subscriber terminals located in a specific call group. For each subscriber terminal there is the possibility of accepting this incoming call while the call is still in progress, ie without a broker or inquiry function. The signaling and control of the service feature is implemented in the private branch exchange using so-called stimulus protocols. This control takes place centrally from the private branch exchange. In contrast, such complex service features are currently not supported or otherwise supported in an open network, ie, for example, no call pickup can be carried out by another subscriber terminal during the call phase. Basically there is the possibility to implement such service features centrally in a public switching center. However, this means an intervention in the public exchanges or the public network.

The invention is therefore based on the object of creating a device and a method for realizing complex service features in a network without influencing the network.

According to the invention, this object is achieved with regard to the method by the measures of patent claim 1 and with regard to the device by the features of patent claim 9.

As a result, the complex service features are implemented decentrally in end devices connected to a network. First, a complex service feature is selected and transmitted as coded information to an additional digital terminal in an information element transmitted transparently by the network. The further digital terminal evaluates this transmitted and coded information and simulates a corresponding service feature. In this way, complex service features can be implemented inexpensively and decentrally in a network without influencing the network, whereby other (already existing) devices can be operated unchanged.

The network is preferably a public ISDN network with D-channel signaling of layer 3 ETS 300 102, which means that every user of the European public ISDN network has the option of cost-effectively realizing complex service features using specially modified end devices.

Advantageous embodiments of the invention are characterized in the subclaims.

The invention is described below with reference to exemplary embodiments with reference to the drawing.

Show it:

Figure 1 shows a communication system for the decentralized implementation of complex service features;

Figures 2A to 2D an E-DSSl signaling protocol for realizing a complex service feature according to a first embodiment;

Figures 3A to 3C an E-DSSl signaling protocol for realizing a complex service feature according to a second embodiment;

Figures 4A to 4C an E-DSSl signaling protocol for realizing a complex service feature according to a third embodiment;

Figures 5A to 5C an E-DSSl signaling protocol for realizing a complex service feature according to a fourth embodiment;

FIGS. 6A to 61 show an E-DSS1 signaling protocol for realizing a complex service feature according to a fifth exemplary embodiment; FIGS. 7A to 7E show an E-DSSI signaling protocol for realizing a complex service feature according to a sixth exemplary embodiment; and

Figures 8A to 8C an E-DSSl signaling protocol for realizing a complex service feature according to a seventh embodiment.

In the following, "call pickup" and "callback" are described as examples of complex service features, an open ISDN network being used as the network, the D-channel signaling of layer 3 of which is based on the Euro-ISDN protocol E-DSS1.

FIG. 1 shows a telecommunication system with such a public network N and a private network P, to which a large number of terminals A, B, C and D are connected. According to FIG. 1, the terminals A to D are, for example, ISDN telephones or video telephones which are connected to the public network N or the private network P via a base connection. It is essential for the present invention that the digital public network N or the private network P does not have to be modified or changed in order to implement the complex service features. Rather, according to the invention, a modification of at least two end devices is sufficient to implement a complex service feature. In the following, we will therefore also speak of decentralized implementation of service features.

According to the present invention, each modified terminal A to D has a transmission unit for transmitting an information element coded according to the invention, which is transmitted transparently by the digital network N, P, ie without checking or changing its data content. Furthermore, each modified digital terminal A to D has a reception Unit for receiving and evaluating the information elements transmitted transparently by the network N, P and a replica unit with which a corresponding service feature can be simulated decentrally and inexpensively.

Figures 2 to 8 each show E-DSSI signaling protocols for realizing the service features "call pickup" and "callback". In FIGS. 2 to 8, messages provided with arrows denote so-called signaling message types which enable the individual terminals A to D to be signaled with the ISDN network N, P in each case.

For clarification, the message types used in FIGS. 2 to 8 are briefly described with regard to their mode of operation:

ALERT "display of an incoming call"

CALL_PROCEEDING "receive all dialing information" CONNECT "accept calls"

CONNECT_ACKNOWLEDGE "Call acceptance confirmed" DISCONNECT "Request for connection termination" RELEASE "Resolution of a connection" RELEASE_COMPLETE "Resolution confirmation"

SETUP "Initiation of a connection establishment"

SETUP_ACKNOWLEDGE "Receipt of the SETUP is confirmed." INFORMATION "Transmission of information, such as dialing information" FACILITY "service request or

Assignment ".

In the message types, a large number of information elements are transmitted, some of which are assigned to the respective message type in brackets in the figures. The information elements used in FIGS. 2 to 8 designate:

CR (call reference) "Identification of a connection (transaction)"

CdNrX (called number X) "Specification of the called number X"

CgNrX (calling number X) "Specifying the calling number X"

Channel "Specification of the channel used"

UUS (user user) "subscriber-to-subscriber information"

SUB (called subaddress) "called subordinate addressing" LLC (low layer compatibility) "compatibility in the lower

Layer "RdNrX (redirected number X)" Specification of the phone number from which the call was diverted "FAC (facility)" Service request or assignment ".

Furthermore, the availability of certain standardized service features is a prerequisite for realizing the present invention. These standardized service features can be:

MSN (multiple "multiple call number of a subscriber number) basic connection" CLIP (calling line identi- "display of the number of the notification presentation) subscriber at the B subscriber" CW (call waiting) "call waiting with display on

Display ".

CD (call deflection) "Call forwarding in the

Call phase "UUS1 (user user signaling sl)" subscriber-to-subscriber

Signaling service 1 " SUB (subaddressing) "subaddressing"

For the decentralized implementation of complex service features, it is particularly important that the information elements (eg UUS, SUB or LLC) in the respective

Message types from the digital network or its switching centers are passed through transparently and without checking. In this context, it should be pointed out that the information elements SUB (subaddress) and LLC (low layer compatibility) are only transmitted transparently by the network N or P in the message types SETUP and CONNECT. The information element LLC (low layer compatibility) is transmitted differently from the standard.

It is now essential for the present invention that a respective modified end device stores information about a desired service feature in coded form in the transparently transmitted information element UUS, SUB or LLC and on the other hand evaluates the information thus obtained and reproduces it according to the information content for certain service features.

Figures 2 to 6 describe D-channel signaling protocols of layer 3 in accordance with ETS 300 102 for the complex service feature "call pickup in a call pickup group". Such a service feature is often referred to in private branch exchanges as a "chief secretary function". According to FIGS. 2 to 6, this "chief secretary function" is simulated in various ways on an ISDN-E-DSS1 terminal connection, without thereby violating the standards valid for the ISDN network N, P.

FIGS. 2A to 2D show an E-DSS1 signaling protocol for realizing a complex service feature according to a first exemplary embodiment. This is an automatic call forwarding in the call phase of an incoming phone call (using a B- Channel). The standardized service feature CLIP (calling line identification presentation), ie displaying the number of the A subscriber at the B subscriber, cannot be activated by the network N or P, for example. Therefore the numbers of the A and B subscribers do not become C-

Participants passed on. However, there arises a problem in that the C subscriber cannot determine whether the SETUP message type arriving at the C subscriber is valid and unique. In the signaling protocol according to FIGS. 2A to 2D, an A subscriber designates a subscriber on terminal A according to FIG. 1 who is, for example, a customer. A B subscriber can be a secretary, for example, who uses the terminal B according to FIG. 1. A C subscriber is a boss of the secretary and uses the terminal C according to FIG. 1. Between the individual terminals or subscribers there is an ISDN network which corresponds to the network N or P according to FIG. 1.

To implement the complex service features described above, only the terminals B and C have to be modified, while a terminal A in the exemplary embodiment according to FIGS. 2A to 2D can be a conventional analog (terminal adapter) or digital terminal.

According to FIG. 2A, a telephone connection from the A subscriber to the B subscriber is initially established in a step S1. Such a connection establishment in the first channel of the ISDN network can be carried out, for example, in one piece (en bloc) or in succession (overlap sending). If the connection is established in one piece (en-bloc), the complete dialing information is transmitted to the ISDN network using the SETUP message type, whereby the network can transmit a SETUP directly to the B subscriber. However, if the dialing information is only gradually received by the ISDN network using the INFORMATION message type, a SETUP_ACK message type is first sent to the A subscriber and the SETUP message type is only received after all dialing information has been received sent to the B subscriber and optionally a message type CALL_PROCEEDING to the A subscriber. The B-subscriber confirms the establishment of the connection with a message type ALERT, which is forwarded to the A-subscriber. In the respective message types, for example, assignments CR for the subscribers and channels used are also sent.

In step S2, the incoming call is now communicated to the C subscriber via an information element coded according to the invention, such as, for. B. UUS, SUB or LLC. According to FIGS. 2A to 2D, this message is sent with the SETUP message type, which is forwarded from the ISDN network to the C subscriber and is confirmed to the B subscriber via the SETUP_ACK message type. Optionally or additionally, the ISDN network can send the message type CALL_PROCEEDING, which indicates that all dialing information has been received.

In an optional step 01, the C subscriber replies, for example, with the RELEASE_COMPLETE message type, as a result of which the ISDN network sends the DISCONNECT message type to the B subscriber. The B subscriber then sends a RELEASE message type to the ISDN network, which confirms the disconnection by means of the RELEASE_COMPLETE message type.

However, step 01 can also be replaced by an optional step 02, whereby the C-subscriber does not answer and the B-subscriber triggers himself. In this case, the terminal B automatically sends a message type DISCONNECT to the ISDN network after a predetermined time, as a result of which the message types RELEASE and RELEASE_COMPLETE are used to reverse the connection in the opposite direction to step 01.

After the connection between subscribers B and C has been broken or released, the information coded according to the invention is evaluated by the C subscriber or in his terminal C. mation UUS, SUB or LLC hereinafter as INFO. According to FIG. 2A, this information "call is pending" was transmitted in the SETUP message type. The evaluated information INFO can now be output visually or acoustically on the terminal C in order to give the C subscriber the opportunity to take over the incoming call from the A subscriber from the B subscriber. According to FIG. 2B, the C subscriber wants to take over the incoming call in a step S3, which is why a coded information element UUS, SUB or LLC is sent to the B subscriber as information (“takeover request”) in the SETUP message type.

In a step S4, this “takeover request” or the confirmation of the previously sent information is evaluated in the terminal B, the standardized service feature CD automatically being used with the message type FACILITY

"Call forwarding" (call deflection) from terminal A to terminal C is requested from the ISD network. To resolve the connection establishment that was initiated by the Ν message type SETUP, the ISDΝ network can either send an Νac direct type SETUP_ACK and / or the Ν message type CALL_PROCEEDIΝG to the C subscriber. In a step S4 *, the terminal C can then resolve the connection establishment itself or wait until the connection is terminated by the ISDN network. In addition, there is the option of opening the connection from terminal B using the message type RELEASE_COMPLETE. In all cases, the connection between the B subscriber and the C subscriber is terminated and in a step S5 a connection from the terminal A to the terminal C is initiated by the network N (or P) via the message type SETUP.

In a step S6, this redirection carried out by the ISDN network is communicated to the B subscriber via the DISCONNECT message type, which in turn causes the connection to the ISDN network to be terminated (RELEASE, RELEASE_COMPLETE). In a step S7, the C subscriber now accepts the call of the A subscriber redirected from the ISDN network, optionally via the message types ALERT and CONNECT are first displayed to the ISDN network and then to the A subscriber the call acceptance. The complex service feature "automatic call forwarding" can thus be implemented without influencing the ISDN network. Furthermore, there are no or only small additional costs or telephone charges, since the transmission of the various information in the selected message types from the network takes place inexpensively or even free of charge, as long as the connection between the terminals involved is not completed.

FIGS. 3A to 3C show an E-DSSl signaling protocol for realizing a complex service feature according to a second exemplary embodiment, automatic call forwarding of an incoming telephone call being initiated with an information element UUS and an acknowledgment for the message types ALERT and DISCONNECT Terminal C is performed. To avoid repetitions, the description of the same or similar signaling sequences as in the first exemplary embodiment is omitted.

In step S10, a telephone connection is again established by the A subscriber in a first channel. According to step S10, all dialing information is transmitted in one piece (en bloc), which is why the SETUP message type is forwarded directly from the ISDN network to the B subscriber and no further dialing information about the INFORMATION message type has to be transmitted. The step S10 otherwise corresponds to the step S1 according to FIG. 2A.

In step S11 according to FIG. 3A, the incoming call to the C subscriber is transmitted via the information element UUS in the message type SETUP. According to step S11, the C-subscriber does not answer, which is why the connection from the B-subscriber is terminated via the DISCONNECT message type. This corresponds to step 02 according to FIG. 2B. However, it can also As in FIG. 2B, step 01 can optionally also be carried out in step S11 according to FIG. 3A, the C subscriber releasing the connection with a message type RELEASE_COMPLETE.

In a step S12, the information element UUS is again evaluated and displayed on the terminal C in order to give the C subscriber the opportunity to take over the call or the call from the A subscriber. Step S12 essentially corresponds to step S3 according to FIG. 2B.

In a step S13, the received information element UUS is evaluated with the request for "accepting the call from A to C" in the terminal B, this via the message type FACILITY and the information element FAC contained therein with the coding CD (call deflection) Call forwarding on the ISDN network requests. In contrast to the exemplary embodiment according to FIGS. 2A to 2D, however, the terminal B sends the message type ALERT to the C subscriber as an acknowledgment, the information “takeover initiated” being transmitted transparently by the ISDN network in its information element UUS.

In a step S14, the switching center delivers the call to the terminal C and acknowledges this to the terminal B. The step S14 essentially corresponds to the steps S5 and S6 of the first exemplary embodiment.

In a step S15, the terminal B acknowledges the successful rerouting via the information element UUS ("successful") of the DISCONNECT message type. The connection is then released by the C subscriber using the RELEASE message type and confirmed by the B subscriber using the RELEASE_COMPLETE message type.

In a step S16, the terminal C accepts the call from the A subscriber, with essentially the same signaling messages as in step S7 of the first embodiment. be carried out. In the present second exemplary embodiment, the use of acknowledgment signals results in improved user convenience with a cost-effective implementation of the “call pickup” service feature.

FIGS. 4A to 4C show an E-DSS1 signaling protocol for realizing a complex service feature according to a third exemplary embodiment. Here, the automatic call forwarding of an incoming telephone call with the information element UUS is transmitted in a message type RELEASE_COMPLETE, while an acknowledgment in the message type SETUP is provided for the terminal device C.

In step S21, a telephone connection from an A subscriber in a first B channel to a B subscriber is again established in accordance with FIG. 4A. Step S20 essentially corresponds to step S10 according to the second exemplary embodiment. In a step S21, the B subscriber in turn transmits the incoming call to the C subscriber via the information element UUS. Step S21 corresponds essentially to step S11 according to the second exemplary embodiment.

In a step S22, the evaluation of the information element UUS transmitted transparently by the ISDN network is again carried out, the same signaling messages as in step S12 according to the second exemplary embodiment being carried out.

In a step S23, the information element UUS indicating the call acceptance is evaluated in the terminal B, which in turn calls the call forwarding from the terminal A to the terminal C at the ISDN network. In contrast to the second exemplary embodiment according to FIGS. 3A to 3C, however, the acknowledgment for the initiation of the call acceptance is carried out with the subsequent direction type RELEASE_COMPLETE sent from the B subscriber to the ISDN network, which in turn forwards the information element UUS with the information "transfer initiated" to the C subscriber via the message type DISCONNECT. The terminal C then terminates the connection to the ISDN network with the RELEASE message type.

A subsequent step S24 corresponds essentially to step S14 of the second exemplary embodiment and serves for the delivery of the call and the acknowledgment by the exchange or the ISDN network. In the event that the call diversion was successful in step S24, the terminal B can acknowledge the successful call diversion in step S25 using the message type SETUP. If, on the other hand, the call diversion could not be carried out, a "takeover unsuccessful" is transmitted to the C subscriber as information in the information element UUS of the message type SETUP.

In a step S26, the terminal C in turn takes over

Call from A-subscriber. Step S26 corresponds essentially to step S16 according to the second exemplary embodiment. This enables a simplified implementation in the terminal C.

FIGS. 5A to 5C show an E-DSSI signaling protocol for realizing a complex service feature according to a fourth exemplary embodiment. According to the fourth exemplary embodiment, automatic call forwarding of an incoming videophone call with two B channels is controlled via the information element UUS. The second B channel is forwarded by means of a time recording unit within a predetermined time.

The signaling steps S30 to S36 correspond to automatic call forwarding for a first B channel (voice channel) and are essentially correct with the Signaling steps S10 to S16 according to the second embodiment. A renewed description of these already known steps is therefore not given here.

However, it should be pointed out that in step S35, in addition to the acknowledgment for the successful call diversion in the terminal B, a time recording unit with a duration of e.g. 10 seconds is started.

In step S37, the connection is now set up for a second B channel (picture channel), essentially the same message types as in step S30 for establishing the connection of the first B channel.

In step S38, however, the timer or time recording unit started in step S35 is checked to determine whether a predetermined time (eg 10 seconds) has already expired. A check is also carried out to determine whether it is a valid second B channel. If the check in step S38 is positive in both cases, i. H. the time recording unit has not yet reached its maximum value and the second B channel is valid, the terminal B automatically requests the call forwarding from the terminal A to the terminal C from the ISDN network without further notification to the C subscriber. This has the particular advantage that in the case of an automatic call forwarding of an incoming videophone call, the two associated B channels are automatically rerouted to the C subscriber without renewed signaling. A delay resulting from the exchange of the different information between the terminals B and C can be further reduced.

FIGS. 6A to 61 show an E-DSSI signaling protocol for realizing a complex service feature according to a fifth exemplary embodiment. Here an automatic call forwarding of an incoming Telephone call in a B channel on request to two other terminals (subscribers) C and D realized.

In steps S41 and S42, a telephone connection from the terminal A to the terminal B and a notification of the incoming call to the terminal C are in turn carried out. The respective message types of these steps essentially correspond to the message types of steps S1 and S2 according to the first exemplary embodiment, which is why a further description is dispensed with.

In an optional step 041, the connection establishment to the terminal C is answered by the latter with the message type ALERT, the terminal B subsequently initiating a termination of the connection via the ISDN network via the message type DISCONNECT.

Optionally, this termination of the connection between the terminal B and C can also be answered or resolved by the terminal C with the message type RELEASE (optional step 042).

Furthermore, instead of the optional steps 041 or 042 in an optional step 043, the terminal C can ignore the message type SETUP in step S42, the termination of the connection again being initiated by the terminal B. This step essentially corresponds to the optional step 02 according to the first exemplary embodiment.

In a step S43, in addition to the notification of the incoming call to the terminal C, the incoming call is communicated to the terminal D. The information exchange about the message types in step S43 essentially corresponds to the information exchange in steps S42 and 043, although steps 041 or 042 can also optionally be carried out after step S43 to include a second and third possibility to answer the SETUP by the D-subscriber.

In a step S44, the coded information of the information element UUS is evaluated and displayed in the terminal C. The C-subscriber wants to take over the incoming call of the A-subscriber from the B-subscriber and tries to control the terminal B remotely, for example, using the SETUP message type. It is important in this exemplary embodiment that, in addition to the takeover request, the place of origin of the takeover request (“takeover call number A from call number C”) is also displayed. In a step S45, this special information of the coded information element UUS is evaluated in the terminal B, a call forwarding from the terminal A to the terminal C being automatically requested from the ISDN network.

In an optional step 044, the request of the C subscriber to accept the call can also be answered with the message type RELEASE_COMPLETE, which is forwarded by the ISDN network with the message type DISCONNECT to the terminal C and is answered by the latter with the message type RELEASE . In the information element UUS transmitted from the terminal B to the terminal C, the information "takeover is initiated" can be transmitted.

On the other hand, in an optional step 045, as an alternative to step 044, the terminal B can answer the request for call acceptance with the message type ALERT, which is transmitted by the ISDN network and also contains the message "Acceptance is initiated" in its information element UUS.

In a step S46, the information element UUS is also evaluated and displayed in the terminal D, a subscriber on the terminal D also wanting to take over the incoming call from the A subscriber from the B subscriber. Terminal D therefore tries the terminal in the same way as in step S44 B remote control via the message type SETUP. In addition to the request for call acceptance, the information of the information element UUS also includes the place of origin for the terminal device D.

In a step S47, the received coded information element UUS is then evaluated. However, since the call has already been taken over by terminal C, the takeover request by terminal D is rejected.

According to an optional step 046, this rejection can take place with the message types ALERT and DISCONNECT, the message "takeover not possible" being transmitted in the information element UUS, for example.

As an alternative to step 046, however, the transfer request can also be rejected in a step 047 with the message types ALERT and RELEASE. Here, the message type ALERT is first transmitted to the terminal D using the information element UUS ("transfer not possible") and then the connection to the terminal D and the ISDN network is terminated using the message type RELEASE.

As an alternative to steps 046 and 047, the transfer request can also be denied according to an optional step 048 with the message type RELEASE_C0MPLETE or simply ignored according to an optional step 049.

In a step S48 and S49, the call switching to the terminal C is carried out by the switching center or the ISDN network, the call forwarding being acknowledged to the B terminal. These steps S48 and S49 essentially correspond to steps S5 and S6 of the first exemplary embodiment.

According to an optional step 050, the terminal B can acknowledge the successful diversion to the terminal C. The in Message types transmitted in step O50 essentially correspond to the message types according to step S25 of the third exemplary embodiment.

On the other hand, as an alternative to step 050, step 051 can be carried out, terminal B transmitting terminal C the successful diversion using the DISCONNECT message type. Step 051 essentially corresponds to step S15 according to the second exemplary embodiment.

In a step S50, the call of the A subscriber is then accepted by the terminal C as in step S16 according to the second exemplary embodiment, as a result of which the call pickup is completed. According to the fifth exemplary embodiment described above, call pickup groups can thus also be implemented decentrally.

FIGS. 7 and 8 describe the implementation of the service features "free call back" and "call back when busy".

FIGS. 7A to 7E show an E-DSSI signaling protocol for realizing a complex service feature according to a sixth exemplary embodiment. According to FIGS. 7A to 7E, this is the realization of the

Service feature "callback in free fall". Such a service feature can be implemented centrally in certain digital networks via the service feature CCNR (completion of calls to no reply). In contrast, the following signaling protocol describes a decentralized one

Realization of this service feature. According to FIGS. 7A to 7E, subscriber A tries to establish a connection to subscriber B. However, subscriber B does not accept the incoming call. After a predetermined time, the attempt to establish a connection to terminal A can be triggered by the ISDN network. The terminal A can now by a correspondingly coded request via the information elements UUS, SUB or LLC, for example in the SETUP message type, cause an automatic call back to terminal B as soon as an action has taken place there (e.g. a connection to terminal C has been established and ended again).

According to FIG. 7A, a telephone connection from terminal A to terminal B is initially established in step S60. Step S60 corresponds essentially to step S1 according to the first exemplary embodiment.

In a step S61, the call is signaled at the terminal B, but is not accepted. According to an optional step 061, there is now the possibility that the terminal A clears the connection to the terminal B in order to subsequently activate a callback. According to a step 062, as an alternative to step 061, however, the connection can also be terminated by the ISDN network, the ISDN network terminating the connection after a predetermined period of time if the terminal B does not accept any calls.

In a step S62, terminal A can now request a call back from terminal B via a correspondingly coded information element UUS, SUB or LLC. In a step S63, the coded information element UUS, SUB or LLC is evaluated by the terminal B, a confirmation for the activated service feature being transmitted. According to step S63, this message "callback active" is transmitted to the terminal A in the information element UUS by the message types RELEASE_COMPLETE and DISCONNECT.

In a step S64 it is assumed that the subscriber of the terminal B uses this and conducts a conversation with the subscriber of the terminal C and then ends it again.

As soon as the conversation with the subscriber of the terminal C has ended, an automatic signaling from the terminal B to the terminal A is carried out in a step S65, whereby the presence or availability of the subscriber of the terminal B is displayed. In this case, preferably not only the information “callback” but also the place of origin “call number B” is also transmitted, as a result of which a clear assignment can be made in the case of a large number of callbacks.

In a step S66, a first possibility for realizing the recall is presented. Here, terminal A ignores the signaling of the SETUP message type and only evaluates the associated information element UUS. In this case, the establishment of the connection is initiated by terminal B using the DISCONNECT message type. As soon as the connection between the terminal A and the terminal B has been broken off, the terminal A can again try to establish a connection to the terminal B in a step S67, whereby the callback is initiated.

Optionally, in a step 063, the terminal A can respond with the message type RELEASE_COMPLETE, as a result of which the connection to the terminal B is terminated. A connection from terminal A to terminal B can then be set up again in a step S67 * in the same way as in step S67.

As a third possibility, in an optional step 064, the terminal A can directly accept the connection from the terminal B, although any charges incurred must be paid by the subscriber of the terminal B.

FIGS. 8A to 8C show an E-DSLI signaling protocol for realizing a complex service feature according to a seventh exemplary embodiment. According to FIGS. 8A to 8C, the service feature "recall when busy" is implemented. This service feature can also be implemented centrally via the service feature CCBS (completion of calls to busy subscriber) from the ISDN network. The However, the embodiment described below describes a decentralized solution.

According to FIGS. 8A to 8C, a terminal A tries to establish a connection to a terminal B, but the terminal B is busy. The terminal A, or the A subscriber, now sends a correspondingly coded request via one of the information elements UUS, SUB or LLC to the terminal B, in order to thereby cause an automatic callback as soon as the terminal B becomes free again. If both B channels are occupied (e.g. for video transmissions), the service feature CW (call waiting, "Call waiting with display on the display") should be enabled on terminal B so that the ISDN network sends the SETUP message type to terminal B. .

In a step S70, the terminal A tries to establish a telephone connection to the terminal B, although this is already connected to a terminal C. The signaling messages of step S70 essentially correspond to the signaling messages of step S1 according to the first exemplary embodiment, but the final message type ALERT is not sent by the terminal B.

Rather, in a step S71, the terminal B rejects the "waiting" connection with the message type RELEASE_COMPLETE. The terminal A then requests a call back to the terminal B via a correspondingly coded information element UUS in a step S72. The step S72 essentially corresponds to the step S62 according to the sixth exemplary embodiment. In a step S73, the transmitted information element UUS is evaluated by the terminal B and the entry of the recall is confirmed. This step S73 essentially corresponds to step S63 according to the sixth exemplary embodiment. In a step S74, the subscriber of the terminal B terminates his connection to the terminal C, as a result of which there is automatically a signaling from the terminal B to the terminal A, which indicates the availability of the terminal B. Step S74 corresponds essentially to step S65 according to the sixth exemplary embodiment. In optional step 071, the same signaling protocols as for steps S66 to S67 * and 063 and 064 of the sixth exemplary embodiment can then be carried out. This results in an accelerated implementation of the "recall" service feature.

The invention has been described above using an E-DSSI signaling protocol. However, it is not limited to this and can rather be applied to all further signaling protocols in a digital network, provided that certain standardized service features are available and certain information elements (such as UUS, SUB or LLC) in corresponding message types from the digital network are transparent (ie without a test). Furthermore, the present invention can not only be used in public and private networks, provided that a decentralized implementation of service features is desired and a corresponding layer 3 signaling protocol is implemented, preferably based on Q.931, such as e.g. NI 1 Bellcore National, FTZ 1TR6, AT&T 505-900-321, Northern Telekom NTS S208 and NTT INS Net64. ISDN telephones have been described above as subscriber terminals, but all other terminals can also be used, e.g. stand-alone devices or computer-aided applications.

Claims

claims

1. A method for the decentralized realization of complex service features of terminals in a digital network (N, P) with the steps: a) selecting a complex service feature in a first terminal (A; B); b) encoding the selected service feature in an information element (UUS, SUB, LLC) transmitted transparently by the digital network (N, P); c) transmitting the coded information element (UUS, SUB, LLC) to a further terminal (B; C); d) evaluating the transmitted information element (UUS, SUB, LLC) in the further terminal (B; C); and e) replication of the evaluated information element (UUS, SUB, LLC) as a complex service feature.

2. The method according to claim 1, so that the information elements (UUS, SUB, LLC) are transmitted in signaling message types (SETUP, RELEASE_COMPLETE, RELEASE, CONNECT, DISCONNECT, ALERT).

3. The method according to claim 1 or 2, so that the encoded information elements (UUS, SUB, LLC) are transmitted in accordance with a Layer 3 D-channel signaling protocol in an ISDN network.

4. The method according to any one of claims 1 to 3, d a d u r c h g e k e n n z e i c h n e t that in step e) a confirmation of the evaluated information element (UUS,

SUB, LLC) via a confirmation information element transmitted transparently by the network (N, P).

5. The method according to any one of claims 1 to 4, characterized in that the complex service feature represents a callback, wherein in step e) a availability of a subscriber is also checked on the further terminal (B); and a corresponding callback information element is transmitted to the first terminal (A) if the availability of the subscriber on the further terminal (B) is determined.

6. The method according to claim 5, which also means that in step e) the callback information element is also evaluated and the callback is carried out in the first terminal (A).

7. The method according to claim 4, so that the complex service feature is a call pickup, in step e) further evaluating the confirmation information element in the first

Terminal (B) and requesting a call forwarding (CD) on the digital network (N, P) is carried out.

8. The method according to claim 7, characterized by detecting a time period between the selection of the complex service feature for a further channel (channel 2) of the same terminal, wherein for the further channel (channel 2) a call forwarding (CD) for the same further terminal ( C) the digital network (N, P) is automatically requested if the detected time does not exceed a predetermined value.

9.Device for the decentralized implementation of complex service features with at least two terminals (A, B) which are connected to a digital network (N, P), so that the at least two terminals (A, B) each have one

Sending unit for sending coded information for the complex service feature via an information element (UUS, SUB, LLC) transmitted transparently by the digital network (N, P) and a receiving unit for receiving and evaluating the information elements transmitted transparently by the digital network (N, P) ( UUS, SUB, LLC), a corresponding service feature being simulated in a replication unit.

10. The device according to claim 9, d a d u r c h g e k e n n z e i c h n e t that the digital network (N, P) is an ISDN network with D-channel signaling of layer 3.

11. The device according to claim 9 or 10, so that the at least two terminals (A, B) furthermore have a time recording unit for recording a service feature request time for the same service features in a further channel (channel 2), the automatically

Service feature is also implemented for the further channel (channel 2) if the detected service feature request time does not exceed a predetermined value.