AT507458A2 - NETWORK ACCESSORIES AND COMMUNICATION SYSTEM - Google Patents

Description

Network access device and communication system

The invention relates to a method for establishing a communication connection to the VPN network via a network of third parties for a subscriber who is remote from a private network (VPN), a network access device for an ISDN fixed network with UUS1 service and / or subaddressing. Service for implementing the method, as well as a communication system comprising at least one ISDN landline, a first network access device and a second network access device. 10 Communication systems comprising a public ISDN landline are well known. Such a communication system, see Fig. 1, in addition to the ISDN landline network 22, a plurality of base terminals 24, which are formed as SO interfaces. In each case a subscriber can be connected to a base connection 24, for example an ISDN terminal 25 or 15 an exchange 26, in particular a private network (PBX) exchange. Via the fixed network 22, a connection between the two subscribers 25 and 26 can be established so that the two subscribers 25, 26 can communicate with each other. If the subscriber is not a terminal 25, but an exchange 26, the connection is established by ei-20 nem connected to the exchange subscribers, which may be a terminal or in turn an exchange with the subscriber 25 via the exchange 26. In this way, for example communication between subscribers of a private network and remote subscribers who are not integrated in the private network, at least via the public fixed network 25 22, without losing or changing the original information available, possible.

In an ISDN communication system, signaling information is first exchanged between the participating devices via a D channel. In particular, this signaling information includes setup messages, connect messages, disconnect messages, and acknowledge messages associated with those messages.

To connect a remote from a private network subscriber of a voice or data network, it is known to tunnel from the subscriber to the private network to be transmitted private services through ISDN dial-up connections through the public landline. This tunneling is done via a built-B channel, i. H. via the traffic channel. A disadvantage of this is the loss of time that arises from the fact that for the transmission of private features, for example, first the B-channel in the public fixed network 5 must be established.

The UUS1 service is an ISDN service that allows to transmit and / or receive limited data as part of a setup message, a connect message, and / or a disconnect message. The information sent in this way from the network access device is available to the other network access device before a B channel has been established. Accordingly, data can be sent from the further network access device to the first network access device via the ISDN fixed network and received by the first network access device before a B channel is established.

The subaddressing is an ISDN or GSM feature that allows an extension of the addressing capacity beyond the ISDN number. In subaddressing, additional information can be transmitted by the caller to the recipient when establishing a connection when establishing a connection as part of a subaddressing message. Since the network does not handle the subaddressing message and transmits it transparently, this message can be freely designed.

When operating communication networks, it happens that participants 25 of a private network can not be directly connected to each other, so that a connection must be established via an intervening network. If a high availability of the connection is required between a remote subscriber and the private network and, if possible, data should be transmitted without long waiting times, the remote subscriber is connected to the private network with a fixed connection to the network therebetween. This is correspondingly expensive. A much cheaper option is to establish the connection via the intermediate network only when needed, via a dial-up connection. To ensure that there are no noteworthy power losses compared to the fixed connection, a fast connection via the intermediate network and a high availability of the established connection must be guaranteed. Blocks of dialing ··· · ·········································································· • · · ··· · ·

Connection should be avoided as much as possible. At the same time, all features of the VPN network must be preserved.

DE 10034319 A1 describes an Internet telephone system in which, with the aid of a 5 UUS message or in a subaddress of the call setting, the predetermined telephone number, the subscriber identification number and the password for an Internet connection from a caller side ISDN terminal adapter to a destination side ISDN Terminal adapters are transmitted. The destination-side ISDN terminal adapter then connects to the destination-10 provider's access point. The determined IP addresses are then used to establish an Internet telephone connection.

However, with the help of this method, it is not possible for a remote subscriber of a private network to be transferred as quickly as possible and securely via a third-party network to a VPN network while maintaining all the features required by other VPN subscribers.

It is known from DE 10257966 A1 how a connection from a telecommunication terminal to a data store is set up by means of user-to-user signaling additional services, an ISDN DSS1-20 protocol being used between the telecommunication terminal and a switching center, and Switching system provides access to the data storage. By means of this method and the associated device, call number-related data present in the data storage can be remotely configured. A disadvantage of this method is that the connection establishment takes too long to be able to use it for a leased line-equivalent connection between a remote VPN subscriber and the VPN network via an ISDN network stored therebetween. In addition, the method is not usable for communication between remote VPN subscribers. 30

Object of the present invention is to provide a method with which it is possible within a very short time, between a remote VPN subscriber and a VPN network, while maintaining all the VPN features, an existing public network structure a commu- munikationsverbindung to accomplish. Furthermore, a communication system is to be created which makes it possible to obtain information, in particular private

tion features to be transmitted over a dial-up connection in a short time via an ISDN landline. Another object of the invention is to provide a network access device by means of which such a communication system can be produced. These objects are achieved by the method according to the invention, a network access device and a communication system according to the independent claims.

Advantageous developments are subject matters of the dependent claims. 10

By means of a UUS1 message, setup information and private features can be transmitted. This allows an accelerated connection establishment between a remote from the private network subscriber and a subscriber within the private network over the ISDN landline in the context of dial-up. For example, a setup message transmitted by the remote subscriber to the first network access device can be transmitted via a UUS1 message to the further network access device as part of the connection setup, and this setup message for an accelerated connection between the further network access device and the the other network access device subscriber connected participants are used.

The transmission of status information makes it possible, for example, to quickly identify failures as part of the connection setup and, if possible, to initiate 25 countermeasures, for example a rerouting.

Similarly, it is also possible to transmit such information as part of a subaddressing message using a su-badressing service. 30

The inventive method according to claim 1 establishes a communication connection between a remote from a private network (VPN) participants and another, connected to the VPN network participants over an ISDN landline. That is, the two participants of the VPN network 35 are not connected directly within the VPN network, but via an intervening ISDN landline. The ISDN network offers UUS1

• κ ··· ···· • · • ··· ·· ···

Service and / or subaddressing service. In order to establish the fastest possible communication connection to a VPN over the ISDN network, without renouncing on features of the VPN network, it is necessary, in addition to the numbers of the caller and the called party in addition features 5 of the private network and information about the requested carrier services exchange. This must be done in such a way that as little time as possible is required to establish a connection.

In a connection setup which is initiated by the remote VPN subscriber via its network access device, this network access device is used by means of a UUS1 message and / or a subaddressing message as part of a setup message, a connect message , and / or a disconnect message via the ISDN landline network to at least one other network access device. From this further network access device, the setup information to a subscriber 15 connected participants forwarded.

According to the setup information relate to information about the requested carrier services, a private network number of the remote subscriber 3a, (Calling-1), a private network number of a subscriber within the private network (Called_1), features of a private network or status information on the subscriber-side connection. Conversely, the first network access device receives call information for establishing a connection, features of the private network and / or status information about the subscriber-side connection from the at least one further network access device. 25 Due to this procedure, all data required for establishing the connection is exchanged so quickly between the participants that the connection is established within the shortest possible time. A user does not notice a significant difference between the realization of his connection over a leased line or the method according to the invention. 30

Claim 2 describes an advantageous embodiment of claim 1. The connection is established in the following steps: - the first network access device replaces the dialed number, "Cal-led_1H, with the number of at least one other Netzzugangsvor-35 direction," Called_2 ", - the first Network access device replaced in the calling number the number of the calling party, BCalling_1 ", with the number of the first network access device," Calling_2 ", - the first network access device packs the information" Calling_r, 5 BCalled_1 ", UUS1_1, MLPP_1 and possibly other protocol elements in a UUS1 Message UUS1_2, - the first network access device dials the at least one further network access device via a landline network connection, the first network access device transmits the information originating from the remote subscriber within the scope of the connection setup by means of the setup message packed in UUS1_2 the at least one further network access device, - the at least one further network access device replaced after receiving the setup message in the Called Number own number, "Cal- 15 led_2", with the dialed number, "Called_1", - replaced at least one other network access device in the calling number is the number of the first network access device, "Cal-ling_2", with the number of the remote subscriber, "Calling_1", - the at least one further network access device unpacks over 20 the UUS1_2 transmitted information "Calling_r," Called_r, UUS1_1, MLPP_1 and possibly further protocol elements, - the at least one further network access device forms the original setup message sent by the remote subscriber based on this information, and 25 - the at least one further network access device transmits this simulated setup message to the selected subscriber in the private network.

According to claim 3, the inventive method provides for the required availability of the compound. For this purpose, the availability of B-channels is checked cyclically during idle times. If one or more channels are available, at least one traffic channel will be kept for a certain period of time and after this time an unused link will be depleted. If several user channels have been set up in stock, they will be phased out one after the other.

Thus, almost any one or more channels for the desired connection are already established at any time before a remote subscriber requests a connection, which also contributes to a time savings in establishing a connection. According to claim 4, a backup function is set up so that, if a connection between a first network access device and a subscriber connected to a further network access device can not be established, the first network access device establishes a connection via a third network access device to which the subscriber also subscribes -10 is closed, is manufactured.

In claim 5, an advantageous embodiment of the method of claim 4 is described. From the other network access device, a UUS1 message is transmitted after a futile attempt to establish a connection with the exchange via the fixed network 15 to the first network access device in the context of a disconnect message. This information about the failure of the connection to the exchange are included. Then, a backup routing is activated by the first network access device by the first network access device, a connection to the third Netzzugangsvor-20 direction is established and from there the connection is forwarded to the subscriber via a second exchange.

In claim 6, a further variant for a backup function is listed. Here offers an additional fourth network access device to which a second 25 participants of the private network is connected, which also has a public number in the public fixed network, the possibility of activating a rerouting. For this purpose, the first network access device is set up with a list containing the public number of the fourth network access device. For the rerouting, the first network access device replaces the Called 30 Number Called_1, which designates the private network number of the second VPN subscriber, with a number Called_2, which represents the public number of the fourth network access device. Thus, according to claim 6 via the public network backup possibility of the VPN. 35 8 ···················· ········ ··· «

Claims 7 to 14 relate to a network access device for implementing the method of the previous claims.

Provided according to the invention is a network access device for an ISDN-5 fixed network with UUS1 service (User-to-User Signaling-1 service) and / or Su-badressing service, wherein the network access device is set up such that in a connection via the ISDN fixed network between the network access device and another network access device information by means of a UUS1 message and / or subaddressing message transfer-10 bar and / or receivable.

The inventive communication system of claims 15 to 19 comprises at least one ISDN landline, a first network access device and a second network access device, wherein first network access device and second network access device 15 are each connected via a network connection to the fixed network for communication via the fixed network.

The invention will be explained in more detail below with reference to exemplary embodiments, which are illustrated by a plurality of figures. Showing:

1 shows a communication system according to the prior art,

2 shows a first communication system according to the invention with two network access devices 25, according to the invention

Fig. 3 is an illustration of a connection establishment between a remote subscriber and a private network via a landline network; Fig. 4 is an illustration of a call setup between one

Private network and a remote subscriber via a fixed network,

5 shows a second embodiment of a communication system including a representation of a connection setup between a subscriber and a private network, 35

6 shows a third embodiment of a communication system including a representation of a connection setup between a remote subscriber and a subscriber 5 of a private network,

7 shows a fourth embodiment of a communication system including a representation of a connection setup between a subscriber of a private network and a subscriber set ab-10,

FIG. 8 is a detailed illustration of the connection setup between a remote subscriber and a private network shown in FIG. 3; and FIG

Fig. 9 is a detailed illustration of a connection structure of the connection setup shown in Fig. 5 between an attached subscriber and a private network subscriber. The same or corresponding elements are provided in the figures with the same reference numerals.

2 shows a first embodiment of a communication system according to the invention. 25

The communication system comprises a landline 2, a first network access device 1a and a second network access device 1b, as well as a first subscriber 3a and a second subscriber 3b. Landline 2 is a public ISDN telecommunications network with UUS1 service operated by a subcontracting network operator (TNB). The first network access device 1a and the second network access device 1b are connected to the fixed network 2 in each case via an SO interface S0-1 or S0-2. The interfaces S0-1 and SO-2 are leased ISDN basic connections here at the TNB. For connection to the fixed network 2 via the basic connections S0-1 or S0-2, the first network access device 1a and the second network access device 1b each have an ISDN NT port (Network Termination Port). ·· ···· ·· 10 ···

The first network access device has an ISDN TE port (terminal equipment port), via which the subscriber 3a is connected via an SO interface. The second network access device 1b has a second ISDN 5 NT port, to which the second subscriber 3b is connected via an SO interface. Due to the ports, the first network access device 1a in FIG. 2 is referred to as SO-BoxTE, the second network access device 1b as SO-BoxNT. The first subscriber 3a (Tln-1) is an ISDN terminal in this embodiment. The second subscriber 3b is formed by a private network with a private exchange PBX 3b. To the switching center 3b a plurality of terminals or other exchanges of the private network are connected, which are not shown in detail in FIG. 15

The first network access device 1a and the second network access device 1b are set up such that information can be transmitted and / or received by means of a UUS1 message when establishing a connection via the ISDN landline 2 in the form of a dial-up connection between the first network access device 1a and the second network access device 1b.

3 shows an illustration of a connection setup between the first subscriber 3a placed here and the second subscriber 3b, in this case the switching center 3b of the private network. The remote subscriber 3a starts the connection setup with a setup message directed to the SO BoxTE. The setup message contains information about the requested bearer services (bearer service = BC), a private network number of the remote subscriber 3a, (calling-1), a private network number of a subscriber within the private network (called_1), and information about features 30 of the private network, here information UUS1_1 and MLPP_1 (MLPP = Multi Level Precedence and Pre-emption). The SO BoxTE 1a is set up so that it replaces the dialed number Called_1 with the number of the SO BoxNT 1b Called_2 in the call number of the setup message. Furthermore, the SO BoxTE 1a replaces the number of the first subscriber 3a 35 Calling_1 with the number of the SO box TE Calling_2 in the calling number. Furthermore, the ·· 11

So Box-1a the information Calling__1, Called_1, UUS1_1, MLPP_1 and possibly other protocol elements in a UUS1 message UUS1_2. Via a dial-up connection, SO-BoxTE 1a dials S0-5 BoxNT 1b via landline 2. As part of the connection setup, the information originating from the remote subscriber 3a is transmitted to the SO-BoxNT 1b by means of a setup message packed in the UUS1_2 message.

The SO-BoxNT 1b is set up in such a way that, after receiving the setup 10 message in the called number, it replaces its own number Called_2 with the dialed number Called_1. Furthermore, the SO-BoxNT in the calling number replaces the number of the SO-BoxTE Calling_2 with the number of the remote subscriber Calling_1. Furthermore, the SO-BoxNT unpacks the information transmitted via UUS1_2 Calling_1, Cal1ed_1, UUS1_1, MLPP_1 15 and possibly other protocol elements and based on this information forms the original sent by the remote subscriber 3a setup message. This replicated setup message is sent to the PBX 3b of the private network. The PBX 3b of the private network thus receives a setup message as it was sent from the remote subscriber 3a. By the transmission of this original setup message in the UUS1 between the SO-BoxTE 1a and the SO-BoxNT over the fixed network 2 by signaling in the first connection setup message, a fast connection setup is achieved. The set-up message sent by the remote subscriber 3a reaches the PBX 3b without a B-channel being established.

FIG. 4 shows an illustration of a connection setup between a subscriber of the private network and the remote subscriber 3a. The Dar-30 position of the participant of the private network was waived.

As part of the connection setup, the PBX 3b sends a setup message to the SO-BoxNT 1b. The setup message contains information about the BC request (BC-Voice) the private network number of the remote subscriber 3a 35 Calling_1 the number of the subscriber of the private network Called_1 and private • · · * 12 • · · * 12

··· • · · · · · Mains line characteristics UUS1_1, MLPP_1 and possibly further protocol elements.

The SO-BoxNT 1b is set up in such a way that it replaces the selected number Called_1 with the number of the SO-BoxTE 1a Called_2 after receiving this Seupup message in the called number. Furthermore, the S0-BoxNT 1b in the calling number replaces the number Calling_1 with the number of the S0-BoxNT Calling_2. Furthermore, the SO-BoxNT 1b packages the information Calling_1, Called_1, UUS1_1, MLPP_1 and possibly further protocol elements 10 in a UUS1 message UUS1_2. Via a dial-up connection via the fixed network 2 with the SO-BoxTE 1a, the SO-BoxTE 1a is sent the thus-formed setup message including a UUS1 message. The SO-BoxTE 1a is set up in such a way that, after receiving the setup message in the called number, it replaces its own number Called_2 with the dialed number Called_1. Furthermore, the SO-BoxTE replaces the number of the SO-BoxNT Calling_2 with the number Calling_1 in the calling number. Furthermore, the SO BoxTE unpacks from the UUS1 message UUS1_2 the elements Calling_1, Called_1, UUS1_1, MLPP_1 and 20 any further protocol elements and from these forms the original setup message sent from the PBX 3b to the SO-BoxNT. The setup message mimicked in this way is subsequently sent to the remote subscriber 3a. The remote subscriber 3a thus receives the setup as it was sent from the PBX 3b. The transmission of this initial setup message by means of a UUS1 message UUS1_2 over the fixed network 2 substantially speeds up the establishment of a connection between a subscriber of the private network and the remote subscriber 3a. 30 The correct replica of the original setup message determines the order and length of information items in the UUS1 message. For example, you can code the individual elements as "Element Type" and assign them a certain length. Such coding is advantageous when there is no connection between the S0 boxes 1a, 1b. For standing connections, the original 13 ··

Setup messages are transmitted transparently through the tuned D channel. Preferably, the elements to be transmitted in the UUS1 message are transmitted with appropriate attributes, e.g. Type of Number, Numbering Plan ID, Presentation Indicator. 5

The network access devices 1a, 1b are set up with a network availability function. The SO boxes 1a, 1b check at idle times, for example when no calls are being made or only a single B-channel is being used, the availability of the fixed network 2, i. the availability of B-channels. 10 For this purpose, the SO boxes 1a, 1b are set up so that they call each other, without building an actual connection, ie a B channel. As part of a connection setup between the SO boxes 1a, 1b is checked whether a B-channel can be built up. If this is not the case because, for example, no user-defined channels are available or will catch Release Causes emp-15, repeated attempts are made to establish an actual connection, that is to say a user-defined channel, by means of redial. If this was achieved, this traffic channel is maintained for a certain time. Likewise, the SO boxes 1a, 1b may be arranged to hold a plurality of payload channels for a certain time. After this time, an unused connection will be lost. Then the network availability is tested again. If several user channels have been set up "in stock", they can be reduced one after the other with a time delay. If, during the degradation of these connections, it becomes apparent through another network availability test that the network availability is limited, the remaining, on-hold, payload channels can be maintained.

Another way to reduce the likelihood of blocking is to apply for disaster relief. 30

Fig. 5 shows a second embodiment of a communication system. The second communication system is constructed according to the communication system shown in Fig. 2, but additionally includes a third network access device 1c and a third party 3c. The third network access device is designed in accordance with the second access device 1b, that is to say the S0-BoxNT-1. The third network access device 1c is also referred to as SO-BoxNT-2 in the following section. The third subscriber 3c is connected to the SO-BoxNT-2 on the subscriber side. The third party 3c is formed here by a second exchange PBX-2 of the private network. The private network thus comprises two exchanges, namely PBX 3b and PBX-2 3c. 5 subscribers within the private network (not shown) are thus two switching centers 3b, 3c available.

In this embodiment, the network access device 1a is set up with a backup function. The backup function is such that if a connection between the first network access device 1a and a subscriber connected to a further network access device, here the SO-BoxNT 1b, here PBX 3b, can not be set up, the network access device 1a establishes a connection via a third network access device, here the SO-BoxNT-2 to which the private network subscriber is also connected her-15.

In this embodiment, no connection establishment between the S0-BoxNT 1b and the PBX 3b is possible, for example, because the PBX 3b has failed. If a connection between the remote 20 subscriber 3a and a subscriber of the private network attempts to establish a connection via the S0-BoxNT 1b and the PBX 3b, then the S0-BoxNT sends it to the PBX 3b via the fixed network 2 after a futile connection establishment to the SO BoxTE 1a back a disconnect message. The S0-BoxNT 1b is set up in such a way that it transmits, as part of the disconnect message 25, a UUS1 message containing information about the failure of the connection to the PBX 3b, here the element "Act_Rerouting". The SO BoxTE 1a is set up to enable backup routing after receiving the disconnect message including the UUS1 message. For this purpose, the SO BoxTE 1a starts a connection to the subscriber of the private network 30 via the SO-BoxNT-2 1c and the second exchange PBX-2 3c and forwards the calls over this.

If the line is again between the first SO-BoxNT 1b and the first exchange PBX 3b, the SO-BoxNT 1b sends status information to the SO-BoxTE 1a in the context of a setup message by means of a UUS1 message. After evaluating the status information, the SO-BoxTE 1a 15 ·· ···· deactivates the rerouting. This is preferably done via an automatic selection of the SO BoxTE 1a by the first SO BoxNT 1b.

The activation of the rerouting is preferably independent of a connection setup initiated by 5 users: As soon as the first SO-BoxNT notices a failure of the connection to the first PBX 3b, it informs the SO-BoxTE via an automatic dialing, here as part of a setup Message integrated UUS1 message containing corresponding status information, for example the element Act_Rerouting. 10

Fig. 6 shows a third embodiment of a communication system. The communication system is constructed according to the first communication system, see FIG. The presentation of the SO-BoxNT 1b has been omitted. In addition, the third communication system comprises a fourth network access device, here a second S0-BoxTE-2 1 d constructed similarly to the SO-BoxTE 1a, to which a second subscriber 3d, here TLN-2 3d, is connected. The second subscriber 3d is a participant in the private network and also has a public number in the public fixed network 2. 20 The SO BoxTE 1a is set up with a backup function, which is activated in the event of a connection failure to the PBX 3b. The activation can be activated within the framework of a connection setup initiated by a subscriber or automatically according to the procedure described in connection with the second communication device, see FIG. 5, for example 25 with an Act_Rerouting element packed in a UUS1 message within a Disconnect Message is sent from the SO-BoxNT 1b to the first SO-BoxTE 1a.

The SO BoxTE 1a is set up with a list containing the public number of the 30 second SO BoxTE-2 1d. For the rerouting, it replaces the Called Number Called_1, which designates the private network number of the second subscriber TLN-2, with a number Called_2, which represents the public number of the S0 BoxTE-2 1d. The remaining structure of the setup message is carried out according to the procedure described in the context of the first communication system. In particular, private network number Calling_1 of the subscriber 3a, private network number Called_1 of the selected second subscriber 16 3d and private network-specific service features are packed in a UUS1 message UUS1_Transit. The SO-BoxTE sends this setup message via the landline 2 to the SO-BoxTE-2 1d. The second SO-BoxTE-2 1d is arranged to replicate the original setup message sent from the first sub-receiver 3a to the first SO-BoxTE 1a. The original setup message is then sent to the second participant 3d. This preserves the features of the VPN network.

FIG. 7 shows a fourth embodiment of a communication system according to the invention. The communication system is according to the first embodiment, see FIG. 2 formed, but in addition includes a fifth additional device 1e, here a backup SO-BoxNT-b 1e, and a third party 3e, wherein the third party 3e a plurality of terminals or a or several exchanges 3c may be. The SO-BoxNT-b 1e 15 is thus assigned to any specific ISDN connection.

The SO-BoxNT-b is set up in such a way that it assumes a backup function if it is detected in the course of establishing a connection between the subscriber 3e and the remote subscriber 3a that there is no connection 20 between the subscriber 3e and the first PBX 3b or the SO -BoxNT-B 1b can be constructed. If this error, which lies within the private network, has been detected, a rerouting is activated within the private network via the backup box SO-BoxNT-b 1e. The connection establishment of the subscriber 3e of the private network with the remote subscriber 3a is analogous to that in the frame 25 of the first communication system, s. Fig. 4, described procedure.

FIG. 8 shows a detailed representation of the connection setup shown in FIG. 3 between a remote subscriber 3a and a private network PBX 3b. The abbreviations ITE, PTE, BNT 30 and FNT used in FIG. 8 stand for "ISDN side TE" "Box-TE side", "Box-NT side" or "Fixed network NT".

In the context of the connection establishment initiated by the subscriber 3a, in a first step the remote subscriber 3a, in this case an ISDN terminal 35, sends a setup message to the SO-BoxTE 1a. The SO BoxTE 1a packs the setup message received from the subscriber 3a into a UUS1 message. In a second step, the UUS1 message is sent to the fixed network 2, for example an exchange of the fixed network 2, as part of a setup message. The landline 2 forwards the UUSI message as part of a setup message to the S0-BoxNT1b in a third step. The 5 SO-BoxNT 1b restores the original setup message of the subscriber 3a and sends it in a fourth step to the PBX 3b.

In a fifth step, the SO BoxTE confirms receipt of the setup message to the subscriber 3a. In a sixth step, landline 2 confirms receipt of the setup message of SO-BoxTE 1a. In a seventh step, the SO-BoxNT confirms receipt of the setup message to the landline 2. In an eighth step, the PBX 3b acknowledges receipt of the setup message of the SO-BoxNT 1b. In a ninth step, the PBX 3b sends a connect message to the SO-BoxNT 1b. In a tenth step, the SO-BoxNT 1b sends a connect message to the fixed network 2. Here, the SO-BoxNT 1b is set up so that it receives information, in particular status information via a connection between the SO-BoxNT and the PBX 3b or a PBX 3b connected private network participants, packed in a UUS1 message, which sends them to landline 2 as part of the Connect message. In an eleventh step, the landline 2 sends a Connect message to the S0-BoxTE 1a, wherein in the context of this Connect message the UUS1 message is carried on. The SO-BoxTE unpacks the received UUS1 message. The information received via the UUS1 message can be evaluated and lead to the initiation of various measures, for example a rerouting. In a twelfth step, the SO BoxTE sends a connect message to the remote subscriber 3a. The entire connection is established via a D-channel of the fixed network 2. The connection between the SO-BoxTE 1a and the SO-BoxNT 1b is achieved by selecting the S0-BoxNT1b through the SO-BoxTE 1a. For this purpose, a list of the public numbers of such SO-BoxNT devices 1b is stored in the SO-BoxTE. 35 18

FIG. 9 shows a detailed representation of the connection setup between a remote subscriber 3a and a private network subscriber of a private network shown in the context of the second embodiment of a communication system in FIG. 5

The remote subscriber 3a initiates a connection to a private network subscriber (not shown) of a private network connected to the central office PBX 3b and to the central office PBX-2 3c. As part of the connection setup sends the remote participants 3a, 10 here an ISDN terminal, in a first step of a setup message to the SO BoxTE 1a. The SO BoxTE 1a packages this data in a UUS1 message. In a second step, the SO-BoxTE sends a setup message for establishing a connection with the SO-BoxNT to the fixed network 2. As part of this setup message, the UUS1 message with the packed information 15 is sent along. In a third step, the landline 2 sends a setup message to the SO-BoxNT 1b, wherein in the context of the setup message the UUS1 message is sent. In a fourth step, the S0-BoxNT 1b recognizes that a connection setup between the SO-BoxNT 1b and the PBX 3b is not possible. 20

In a fifth step, the SO BoxTE 1a sends a setup confirmation to the remote subscriber 3a. In a sixth step, the landline 2a sends a setup confirmation to the SO-BoxTE 1a. In a seventh step, the SO-BoxNT sends a setup confirmation to the fixed network 2. 25

In an eighth step, the SO-BoxNT sends a disconnect message destined for the SO-BoxTE to the fixed network 2. The SO-BoxTN packs the information that a connection to the PBX 3b is not possible into a UUS1 - Message sent as part of the disconnect message. In step 30, the landline 2 sends a disconnect message to the SO-BoxTE 1a, the UUS1 message being forwarded as part of the disconnect message. The SO box E1 unpacks the UUS1 message and initiates a rerouting prompted by the information contained in the UUSI message. 35 ·· 19

As part of the rerouting, the SO-BoxTE sends in a tenth step a setup message intended for a second SO-BoxNT-2 1c to landline 2. The public number of the SO-BoxNT-2 1c is also in one List of the SO-BoxTE 1a deposited and provided as an alternative in the event of a connection failure on the side of the SO-BoxNT 1b. As part of the setup message to the fixed network 2, the original UUS1 message containing the information on the remote subscriber 3a is also sent. In an eleventh step, the landline 2 sends a setup message to the second SO-BoxNT 1c. As part of the setup message, the UUS1-10 message is forwarded to the second SO-BoxNT-2 1c. The second SO-BoxNT unpacks the UUS1 message and establishes the original setup message sent from the remote subscriber 3a to the SO-BoxTE. In a twelfth step, the second SO-BoxNT 1c sends the restored setup message to the second PBX-2 3c. 15

The described connection establishment between the SO BoxTE 1a and the S0 BoxNT boxes 1b, 1c takes place via a D channel. A B channel has not yet been established at this time. In an alternative embodiment, the remote subscriber 3a is formed by an exchange of another private network. Accordingly, the SO BoxTE 1a is formed as SO BoxTN.

In another alternative embodiment, the SO BoxTE boxes 25 1a, 1d and the SO BoxNT boxes 1b, 1c, 1e are formed by an SO box having all the functionalities. That is, the SO box can be used both as S0-BoxTE 1a and as SO-BoxNT 1b, etc.

The SO boxes have suitable electronic components and programs for the described functionalities. 30

The private network is preferably a private network according to a GSM-R standard (GSM = "Global System Mobile", R = "Railway").

The described communication systems with the network access devices 35 1a, 1b, 1c, 1 d, 1 e allow the establishment of a connection between a remote subscriber of a private network and a private network via a public 20 20 ··· «· · · · · · · · • ··· · · · t ·· «public network using a dial-up connection. The advantages of the described communication systems are that the D-channel signaling is transmitted transparently over the dial-up connection, that the connection times are short, and that own numbering plans and features can be maintained. Other benefits include minimizing dial-up blocking probability and backup capabilities.

By coding the voice and tunneling through the fixed network 2, the communication systems described above may additionally be configured to allow more than two parallel connections to be switched from a remote subscriber to the private network. This increases the performance of the connection.

Furthermore, the increase in the number of possible connections for administration purposes is usable. For example, parallel data connections can be set up which can be forwarded directly to a data network at an SO box on the private network side without having to use a voice infrastructure of the private network. This allows for increased management polling and any data access. 20

In a further embodiment, instead of a UUS1 service for the transmission of information during connection setup, a sub-stationing service provided by the fixed network is used. The transmission of the information in this case instead of UUS1 messages with Su-25 badressing messages takes place in a similar manner.

It is also possible to use UUS1 service and subaddressing service together in parallel.

I

Claims (20)

1. A method for establishing a communication connection between a subscriber (3a) remote from a private network (VPN) and a further subscriber (3b) connected to the VPN network via an ISDN landline network (2) with UUS1. Service and / or subaddressing service, wherein in a connection setup for the remote VPN subscriber (3a) from a network access device (1a) by means of a UUS1 message and / or a subaddressing message, as part of a setup message, a Con- 10 nect message, and / or a disconnect message over the ISDN landline (2) to at least one other network access device (1b, 1c, 1 d, 1e) and to a subscriber-connected subscriber (3b) setup information is transmitted characterized in that the setup information includes information about the requested bearer services, a private subscriber number of the remote subscriber 3a, (calling-1), a private network number of a subscriber within the private network (Called_1), features of a private network and / or status information on the subscriber side port (3a), and vice versa call information for a connection, features of a Pri-20 vatnetzes and / or status information on a subscriber-side port (3b) of one another network access device (1b, 1c, 1 d, 1 e) are received. 2. A method for establishing a communication link according to claim 25, wherein • the network access device (1a) replaces the dialed number, nCalled_1u, with the number of the at least one further network access device (1b, 1c, 1d, 1e), "Called_2" in that - the network access device (1a) in the calling number replaces the number of the first subscriber (3a), "Calling_r, with the number of the network access device (1a)," Calling_2 ", - the network access device (1a) the information" Calling_1e , "Cal-led_1", UUS1_1, MLPP_1 and possibly further protocol elements packed in a UUS1 message UUS1_2, 35 - the network access device (1a) dials the further network access device (1b) via a landline telephone network (2), the network access device (1a) transmits the information originating from the remote subscriber (3a) to the further network access device (1b) by means of the setup message packed in the UUS1_2, the at least one further network access device (1b, 1c, 1d, 1e) upon receipt of the setup message in the called number its own number, "Called_2", replaced with the dialed number, BCalled_1 ", the at least one other network access device (1b, 1c, 1 d, 1e) in the calling Number replaces the number of the network access device (1a), "Caling_2", with the number of the remote subscriber, BCalling_1 ", the at least one further network access device (1b, 1c, 1d, 1e) transmits the information BCalling_1" transmitted via the UUS1_2, BCalled_1 ", UUS1_1, MLPP_1 and possibly further protocol elements unpacked, the at least one further network access device (1b, 1c, 1d, 1e) based on this information the u original setup message transmitted by the remote subscriber (3a), and from the at least one further network access device (1b, 1c, 1d, 1e) this simulated setup message is transmitted to the selected subscriber in the private network. 3. A method for establishing a communication link according to one of the preceding claims, wherein at rest cyclically the availability of B-channels is checked and at least one user channel for a certain 25 time is kept in stock and after this time an unused connection is reduced, wherein, if several Nutzkanäle have been built on stock, these are temporally offset successively reduced. 4 ··················································· 4. A method for establishing a communication connection according to one of the preceding claims, wherein a backup function is set up so that when a connection between a network access device (1a) and a subscriber connected to another network access device (1b) can not be established, the network access device 35 (1a) establishes a connection via a third network access device (1c, 1d) to which the subscriber is also connected. 5. A method for a backup function according to claim 4, wherein the network access device (1b) after a failed attempt to establish a connection with the switching center (3b) via the fixed network (2) to the 5 network access device (1a) as part of a disconnect message a UUS1 message is transmitted containing information about the failure of the connection to the exchange (3b), whereupon the network access device (1a) activates a backup routing by connecting from the network access device (1a) to the network access device (1c) is established and from there the connection is forwarded to the subscriber via a second exchange (3c). 6. A method for establishing a communication connection according to one of the preceding claims, wherein a backup function is set up, such that when a connection between a first network access device (1a) and a subscriber connected to another network access device (1b) are not established a connection can be established by the network access device (1a) via a fourth network access device (1d) to which the subscriber is connected to the public ISDN fixed network, wherein the first network access device (1a) is set up with a list, which contains the public number of the fourth network access device (1 d) and for the rerouting of the first network access device (1a) the Called Number Called_1, which indicates the private network number of the second VPN subscriber by a number Cal-25 led_2, the public number the fourth network access device (1d) is replaced. 7. Network access device (1a) for an ISDN fixed network (2) with UUS1 service and / or subaddressing service, wherein the network access device (1a) 30 is set up in such a way that it is connected when a connection is set up by a remote VPN subscriber (3a). by means of a UUS1 message and / or a subaddressing message, as part of a setup message, a connect message, and / or a disconnect message via the ISDN landline network (2) to at least one further network access device (1b, 1c, 35 1 d, 1 e) and to a subscriber-connected subscriber (3 b) transmits setup information, characterized in that the setup 5 24 10 15 20 25 30 ♦♦ ···· • ··· Information Information about the requested carrier services , a private network number of the remote subscriber 3a, (Calling-1), a private network number of a subscriber within the private network (Called_1), features of a private network and / or status information about the subscriber refer to reverse connection (3a), and vice versa call information for a connection, features of a private network and / or status information on a subscriber-side port (3b) from another network access device (1b, 1c, 1d, 1e) receives. 8. The network access device according to claim 7, wherein - the network access device (1a) replaces the dialed number »Called_r with the number of the at least one further network access device (1b, 1c, 1d, 1e),« Called_2 », - the network access device (1a ) in the calling number the number of the first subscriber (3a), BCalling_1 ", with the number of the network access device (1a)," Calling_2 "replaced, - the network access device (1a) the information" Calling_r, "Cal-led_1", UUS1_1 , MLPP_1 and possibly further protocol elements packed in a UUS1 message UUS1_2, - the network access device (1a) dials the further network access device (1b) via a landline telephone network (2), - the network access device (1a) as part of the connection setup by means of the in the UUS1_2 packetized setup message transmits the information originating from the remote subscriber (3a) to the further network access device (1b), - the at least one further network (1b, 1c, 1d, 1e) upon receipt of the setup message in the called number its own number, "Called_2", replaced with the dialed number, "Called_1", - the at least one other network access device (1b, 1c , 1d, 1e) in the calling number the number of the network access device (1a), "Cal-ling_2", replaced with the number of the remote subscriber, nCalling_1 ", - the at least one further network access device (1b, 1c, 1d, 1e) information transmitted via the UUS1_2 "Calling_1", "Called_r, UUS1_1, MLPP_1 and possibly further protocol elements unpacked, 35 2 $ ································································································· The at least one further network access device (1b, 1c, 1d, 1e) simulates the original setup message transmitted by the remote subscriber (3a) on the basis of this information, and - the at least one further network access device (1b , 1c, 1d, 1e) 5 transmits this replicated setup message to the selected subscriber in the private network. 9. Network access device according to one of the preceding claims 7 or 8, wherein the network access device (1 a, 1 b, 1 c, 1 d, 1 e) is set up 10 that compresses by means of a UUS1 message and / or subaddressing message to be transmitted information for transmission become. 10. The network access device according to claim 1, wherein the network access device is configured with a network availability function, wherein the network availability function is such that the network access device in the context of a connection establishment prior to an actual connection establishment to a further network access device (1b) checks whether one or more channels are available for the connection in the fixed network (2) and, if 20 or too few channels are available, repeatedly tries to establish an actual connection to the further network access device (1b ) and, if an actual connection has finally been established, maintains it for a certain time. 11. Network access device according to at least one of the preceding claims 7 to 10, wherein the network access device (1 a) is set up with a network availability function, wherein the network availability function is such that the network access device (1 a) cyclically checks the availability of B-channels in idle times and at least a useful channel for a certain time keeps in stock, and after this time degrades an unused connection, which, if several user channels have been built on stock, these temporally offset degrades successively. 12. Network access device according to one of the preceding claims 7 to 35 11, wherein the network access device (1 a) is directed with a backup function, wherein the backup function is such that when a Ver 2 $ • ·· ··· "••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• The network access device (1 a) establishes a connection via a third network access device (1 c, 1 d), to which the subscriber is also connected 5, manufactures. 13. The network access device with a backup function according to claim 12, wherein the backup function (1a) is arranged such that it after a futile attempt to establish connection with the switching center (3b) over 10 the landline (2) to the network access device (1a) in the context of Disconnect message transmitted a UUS1 message containing information about the failure of the connection to the exchange PBX (3b), whereupon the network access device (1a) activates a backup routing by establishing a connection to the network access device (1c) and this 15 forwards the connection to the subscriber via a second exchange (3c). 14. The network access device according to at least one of the preceding claims 7 to 13, wherein the network access device (1 a) is addressed with a list 20 containing the public number of a fourth network access device (1 d), wherein the network access device (1 a) for a rerouting the Called Number Called_1, which designates the private network number of the second subscriber TLN-2, is replaced by a number Called_2, which represents the public number of the fourth network access device (1d), while retaining the VPN features. 15. Communication system, comprising at least one ISDN landline network (2) with UUS1 service and / or subaddressing service, a first network access device (1a) according to at least one of the preceding claims 7 to 14 30 for a first subscriber (3a) and at least one A second network access device (1b, 1c, 1d, 1e) according to one of the preceding claims 7 to 14 for a second subscriber (3b), wherein the first network access device (1a) and the second network access device (1b, 1c, 1d, 1e) each have a network-side Connection to the fixed network (2) are connected for a Kom-35 communication via the fixed network (2) and the first subscriber (3a) via a subscriber-side connection of the first network access device to the first • ····· • · · · ··· The network access device (1a) is connected, and the second station (3b) is connected via a subscriber - side connection of the second network access point (3a) Gear device (1b) to the second network access device (1b) is connected. 5 16. Communication system according to claim 15, additionally comprising a third network access device (1c, 1d, 1e) according to at least one of the preceding claims 7 to 14, which is connected to the fixed network (2). Communication system according to one of claims 15 to 16, wherein the subscriber (3a, 3b, 3c, 3d, 3e) is at least one terminal (3a, 3d, 3e) or an exchange (3b, 3c). Communication system according to claim 17, wherein the exchange (3b, 15 3c) is a private network exchange (3b, 3c). The communication system of claim 18, wherein the private network is a GSM-R network. 20 05. Nov. 2Π09