EP1305958A1

EP1305958A1 - Switching method for transmitting useful data packets and associated signaling unit

Info

Publication number: EP1305958A1
Application number: EP01953893A
Authority: EP
Inventors: Ole Droz
Original assignee: Siemens AG; Nokia Siemens Networks GmbH and Co KG
Current assignee: Nokia Solutions and Networks GmbH and Co KG
Priority date: 2000-08-02
Filing date: 2001-07-09
Publication date: 2003-05-02
Also published as: WO2002011458A1; US20030026274A1

Abstract

The invention relates to a method according to which a signaling unit (10) contains at least two connection units (20, 22) that are used for setting up a connection for transmitting useful data in data packets. The connection units (20, 22) each terminate the signaling to one of the terminals involved in the data transmission. The connection units exchange internal signaling messages among one another. This enables the signaling to be carried out in a simple manner.

Description

description

Method for switching for the transmission of user data packets and associated signaling unit

The invention relates to a method for switching for the transmission of user data packets. The user data are transmitted in data packets in a data transmission network. The transmission takes place on the basis of data packets. Although data packets can also be transmitted in circuit-switched networks, the transmission and forwarding between the network nodes then takes place not on the basis of data packets but on the basis of time slots.

A data packet usually contains a packet header and a packet body. The packet header contains information on forwarding the data packet, for example a destination address and a sender address. There are also data packets that contain signaling information in the packet header that is required for transmission according to protocols of higher protocol layers. The user data is in the package trunk. Examples of networks in which user data are transmitted in a packet-based manner are the ATM network (Asynchronous Transfer Mode) and the Internet or so-called intranets, in which the data packets are transmitted in accordance with the Internet protocol.

In addition to the networks in which data packets are transmitted, there are also circuit-switched networks. The exchange contains a connection setup phase in which network resources are used for the connection and in which various transmission channels are interconnected. The data is then transmitted and forwarded in time channels. In the connection clearing phase, the occupied resources are released again, whereby the transmission channels are separated from each other again. In networks transmitting data packets, communication is also carried out at higher protocol levels, ie there is a connection establishment phase, a transmission phase and a connection termination phase. Signaling protocols are used for this. So far, the signaling has basically been completed in the terminals, ie signaling messages are generated there for the first time and responses to received signaling messages are sent. Examples of such end devices are service use computers, so-called servers, and service provision computers, so-called clients.

In addition, gateway units are known which connect packet networks and circuit-switched networks. Such a gateway unit is known for example from the standard H.323 (02/98) "Packed Based Multimedia Communications Systems" of the ITU-T (International Telecommunication Union - Standardization Sector Telecommunication). The gateway unit is also referred to as a gateway in this standard. The gateway unit completes the signaling on each side, i.e. for two fixed ones

Protocols. On the packet network side, signals are signaled, for example, in accordance with the H.323 protocol and on the side of the circuit-switched network in accordance with the ISUP protocol (ISDN User Part).

It is an object of the invention to provide an improved method for switching for the transmission of user data packets. In addition, an associated signaling unit, an associated program and a data carrier and a data network message are to be specified with this program.

The object relating to the method is achieved by the method steps specified in patent claim 1. Further developments are specified in the subclaims.

In the method according to the invention, a signaling unit contains at least three connection units which are used in the Establishing a connection for the transmission of user data in data packets. The user data is forwarded in data packets of a network that transmits user data on the basis of data packets. The connection units each complete the signaling to one of the terminals involved in the data transmission. The signaling messages arriving at one connection unit for the transmission of the data packets are forwarded to the other connection unit with the aid of internal signaling messages defined for the signaling unit.

The internal signaling messages are transmitted in accordance with an internal signaling protocol. The internal signaling protocol forms an interface between the two signaling protocols that are closed to the outside on the connection units. The internal signaling protocol is defined in such a way that it can be used both between connection units that terminate the same signaling protocol externally and between connection units that terminate externally in different signaling protocols. On the one hand, modularization is achieved by specifying the internal signaling protocol and the internal signaling messages. This modularization means that connection units for individual external signaling protocols can be developed independently of one another. Modularization also allows the signaling unit to be adapted to different tasks with little effort.

A terminal is considered to be a unit that generates electrically or optically transferable data with the aid of a converter unit, for example with the aid of an acoustic converter unit or with the aid of an image converter unit. A terminal is also a unit that generates acoustic signals or image signals from optical or electronically received data with the aid of a converter unit. The end devices are usually used by participants. A third type of terminal are units that automatically generate or automatically evaluate user data. This type of terminal can also be located in the signaling unit itself, in other signaling units or in other network nodes.

In the method according to the invention, the connection units can optionally be connected to one another. This measure ensures that the rigid connection between the connection units, which was previously customary in signaling for packet-based networks, can be removed. This opens up the possibility of arranging more than two connection units in a signaling unit and connecting them depending on the requirements for the signaling unit. The requirements change, for example, depending on the load or due to other circumstances. If, for example, one connection unit fails, another connection unit can be connected to the partner connection unit instead.

According to a second aspect, the object relating to the method is achieved by the method specified in claim 2, which is technically closely related to the method according to claim 1.

In the method according to the second aspect of the invention, a signaling unit contains at least two connection units which are used when establishing a connection for the transmission of user data in data packets. The user data is forwarded in data packets of a network that transmits user data on the basis of data packets. The connection units each complete the signaling to one of the terminals involved in the data transmission in accordance with a signaling protocol for circuit-switched transmission of user data. The signaling messages arriving at a connection unit for the transmission of the data packets are "

4-1 co

• rH

SH cd a u

•H

Φ

IH iH

Φ

N

4-J

Φ

S d

Φ

-μ rH

Φ

4-1

^• H a

LO O LO o O o LO rH rH CM <M ro m

a port number, which designates a receiving unit of a terminal, and a coding identifier, which designates the coding type used when sending data packets to a terminal.

Alternatively, several signaling messages are used, each of which contains only one of the information elements mentioned. This facilitates a conversion from the external signaling protocols or a conversion to the external signaling protocols.

In one embodiment, the signaling unit contains further connection units which, however, serve to switch connections for the transmission of user data in a circuit-switched network and thus signal according to protocols for circuit-switched networks. The other connection units use the same message interface for exchanging the internal signaling messages as the connection units which mediate the transmission of user data packets. The same signaling messages are used in particular to set up a connection between the different connection units. However, the content of the signaling messages differs depending on the connection unit. This measure means that only one interface has to be defined for the transmission of user data for circuit-switched networks and for the transmission in packet networks. This provides the prerequisite for being able to offer both types of mediation for the participants with considerably less effort.

In a next development, at least one of the connection units involved in establishing the connection works in accordance with the ISUP protocol (ISDN User Part) or a protocol based thereon. The core of the ISUP protocol is specified in particular in the Q.763 and Q.764 standards. Through the inclusion of connection units, which according to the ISUP protocol Completing the signaling to the outside, already proven connection units can be used for switching in the transmission of user data packets and thus for a new task. This saves development effort. The connection units used hitherto only need to be expanded by a few functions, for example a function for determining an Internet address and functions for controlling a control unit which is connected to a packet-switching network. A network transition unit for converting the user data can be reached via the control unit.

If both connection units involved in establishing the connection work in accordance with the ISUP protocol, the signaling unit can be switched between two conventional switching centers of the circuit-switched network. If all three connection units involved in establishing the connection work in accordance with the ISUP protocol, there are options when establishing a connection for transmission in data packets. If necessary, the two connection units signal according to different protocol types.

If one or two of the three connection units signal according to a signaling protocol for a packet network, there is a choice between protocol classes and not only between protocol types when establishing a connection.

In a next embodiment, at least one of the connection units involved in establishing the connection works according to an ISUP protocol supplemented by information elements, which enables the transmission of the following information:

an address at which the one terminal can be reached in the packet-switched network and / or a port number which designates a receiving unit of a terminal and / or a type of coding which is to be used when sending data packets to a terminal. When the ISUP protocol is supplemented, the transport mechanisms specified in the Q.765 standard are preferably used, for example the container structure BAT (Bearer Association Transport) specified there. This measure allows two

Use signaling units from different operators for switching a transmission path for user data packets. This is particularly necessary if the gateway units are controlled by signaling units in different countries. Within a signaling unit there is, for example, a connection unit that works according to the extended ISUP protocol and a connection unit that works according to the ISUP protocol.

In a next development, at least one of the connection units involved in establishing the connection completes the signaling in accordance with a signaling protocol for a packet-transmitting data network. A terminal or another unit in a data packet transmitting network is connected to the connection unit directly or via further signaling units. With this measure, the signaling can be carried out in sections or completely using a network transmitting data packets. Methods are carried out in which two or three line units also signal according to a signaling protocol for packet networks. The signaling protocols can differ. This increases the options for establishing a connection.

In an embodiment with a connection unit that works according to a signaling protocol for a packet-transmitting data network, the signaling protocol is a protocol for signaling with a terminal, preferably the protocol H.323, the protocol SIP (Session Initiation Protocol) or the protocol MGCP ( Media Gateway Control Protocol). The protocol H.323 was established by the ITU-T. The SIP protocol and the MGCP protocol were developed by the IETF (In-

LO o LO O LO O LO rH rH CM CM n 00

The MGCP (Media Gateway Control Protocol) protocol is preferably used as the transition unit, see RFC2705.

In one configuration, the signaling unit contains a plurality of control units, each of which is assigned to a connection unit. By using separate control units in the exchange for the transmission of the same user data, the half-call model can also be used for user data transmitted in packets. This means that the advantages associated with the half-call model can continue to be used.

In another development, a connection unit contains at least two sub-connection units that exchange internal signaling messages with one another. In this case, a partial connection unit converts in the lower protocol layers from the internal signaling protocol to the internal signaling protocol, different messages occurring in higher protocol layers. The training is used, for example, to include a control unit.

In a next development, the user data are forwarded without a connection by the network nodes of the packet-transmitting network, preferably in accordance with the Internet protocol. Alternatively, the user data are forwarded by the network nodes of the packet-switching network in a connection-oriented manner, preferably in accordance with the ATM protocol (Asynchronous Transfer Mode). Connectionless or connection-oriented thus refers to the network layer of the so-called OSI model (Open Systems Interconnection).

The invention also relates to a signaling unit which carries out the steps of the method according to the invention or its further developments. The technical effects mentioned above also apply to the signaling unit. In a further development, the signaling unit is part of a switching center for a circuit-switched network. This means that user data is transmitted in time channels in the exchange. However, the switching center also contains functions for switching a transmission path for user data packets. The user data packets themselves are not forwarded via the exchange, but via the network transmitting the data packets. Within the exchange, however, the same internal signaling messages are used for both types of signaling.

The invention further relates to a program, when executed with the aid of a processor, the steps of the method according to the invention or its further developments are carried out. The program is stored in a memory module, for example, or is transmitted over the Internet.

Exemplary embodiments of the invention are explained below with reference to the accompanying drawings. In it show:

1 shows a switching center with several line units,

FIG. 2 functional units of the switching center for connecting an H.323 terminal to a conventional telephone network,

FIG. 3 functional units of the switching center in the case of conventional interoffice signaling and segmental data transmission over the telephone network, the Internet and again over the telephone network,

FIG. 4 functional units of two switching centers for switching a section over the telephone telephone network, data transmission over the Internet and again over the telephone network, and

FIG. 5 functional units of two switching centers for the switching of data transmission in sections over the Internet and the telephone network.

FIG. 1 shows a switching center 10 with a plurality of connection units 12 to 22. The connection units 12 and 14 are used to connect ISDN subscribers. The DSS1 (Digital Signaling System No. 1) protocol is used as the transmission protocol between the connection unit 12 or 14 and the connected subscribers.

The connection unit 16 is used to connect analog subscriber connections. The connection unit 18 is used to connect the lines leading to a further switching center, which are also referred to as a trunk. The ISUP protocol (ISDN User Part) is used as the signaling protocol between the exchanges.

The connection units 20 and 22 are connection units which have not previously been used in switching centers. The function of these connection units is explained in more detail below.

The switching center 10 also contains a main switching matrix 24 and a central processor 26. The connection units 12 to 22 and the central processor 26 are connected in this order to the main switching matrix 24 via connecting lines 28 to 44, the connecting units 20 and 22 each having two connecting lines 36 and 38 or 40 and 42 are connected to the main switching matrix. The switching matrix 24 contains at least one time switching stage and at least one space switching stage. With the help of the main switching matrix 24, signaling connections and user data connections can be made switch between the connection units with each other and between the connection units and the central processor 26. The coupling processes are controlled by the central processor 26.

For the transmission of signaling messages via the main switching matrix 24, internal signaling messages are used which have been defined for the switching center 10 in accordance with an internal protocol. The internal protocol is similar to the ISUP protocol, but sometimes also differs from this protocol. With the help of the internal signaling protocol, received messages can be mapped in accordance with external signaling protocols and forwarded to other connection units. These line units then forward the messages again in accordance with external signaling protocols. The internal signaling protocol also contains messages for establishing and closing a connection between different line units 12 to 22. The internal signaling messages have a uniformly structured message header, in which e.g. the instance number of the call and the type of message are specified. The actual information is transmitted in the message body.

If, for example, a subscriber TlnA connected to the connection unit 12 dials the number of a subscriber TlnB connected to the connection unit 14, the connection unit 12 receives a setup message in accordance with the DSS1 protocol. According to the protocol, this message is confirmed to the subscriber TlnA with a setup ACK message. The connection unit 12 now begins to search for a partner connection unit within the switching center 10. For this purpose, it establishes a signaling connection to the central processor 26 with the aid of internal signaling messages. The connection unit 12 transmits the telephone number of the subscriber TlnB to the central processor 26. The central processor 26 determines a partner connection unit based on the telephone number. in the exemplary embodiment, the connection unit 14. This is communicated to the connection unit 12 via internal signaling messages. The connection unit 12 then establishes a signaling connection 46 to the connection unit 14 and forwards the received setup message to the connection unit 14 using an internal signaling message. The connection unit 14 then signals to the terminal of the subscriber TlnB a setup message in accordance with the DSS1 standard.

In contrast, if the subscriber TlnA wants to reach a subscriber who is connected to a switching center other than the switching center 10, the central processor 26 mediates the connection unit 18 as the partner connection unit. In this case, an internal signaling connection 48 is established between the connection unit 12 and the connection unit 18 connected.

The connection unit 20 is used to convert between the ISUP protocol and the internal protocol. Implementation takes place in a TRUNK unit 50. In addition, the connection unit 20 contains an IP control unit 52 (Internet Protocol) which signals externally in accordance with a signaling protocol for packet-transmitting data networks, namely in accordance with the Internet protocol. The IP control unit 52 serves to control a gateway unit, which is explained below with reference to FIG. 2. The IP control unit 52 also signals towards the main switching matrix 24 in accordance with the internal signaling protocol. This makes it possible to connect the TRUNK unit 50 and the IP control unit 52 via an internal signaling connection 54.

The connection unit 22 contains a partial connection unit 56 and an IP control unit 58. The partial connection unit 56 is used to connect an H.323 terminal with the interposition of the IP control unit 58. Between an H.323 terminal and the IP control unit 58, according to the protocol LO o LO o LO o LO rH rH CM CM 00 00

1 a Φ 1 rH 1 1

4-1 Φ 1 73 φ 1 φ Φ d cd 4-1 φ 1 4-1

Φ dd 1 O Φ tn CO tn 1 4-1 SH dd 1 SH tn 4H Xi in -H 4-1 υ 1 l • H ^• H Di φ 1 4- ⁾ φ 4-> cd φ -rH 4-1 Φ O Φ co d CQ m U in SH d Φ d 4-> • 0 ⁾ 1 P dd Di co Φ d rH • H 73 • H a ^• H du 73 d &: cd • H rN Φ Φ to φ Φ Φ φ d tn 4-1 d rH SH d P SH Φ 4-1 φ cd a iH

© d X! tn O 4-> rH CD d tM φ xi cd Φ SH Xi 4-J d Φ φ Φ XI o ^• rH O dd rH -HP 4-1 O d 4-1 o 4-1 Ü 4-1 • EH Φ υ N Φ Λ d -HD u ω Φ co cd Φ d Φ co <! SH 4-1 r- \ rH Φ o 10 co co d XI ^• H 4-1 d cd Φ 73 cd

O -rH tn 4-J CM rH Es d -H 4-1 to rH to SH to SH d ^• H tn -μ 4-1 53

A4 P c φ w to da 4-J 4-1 Φ tn φ cq ^• H cd P XI d Φ 8 cd XI Xi 1

H tM N 73 tn d 54 • H -H oil rH d 73: cd S d d Φ 73 u υ Di α. d tM xi o SH φ Φ Φ -Q d d d

4-1 υ rH Φ & a PQ> XI a ΪH cd a rH cd tn a tM d ^• H d

Φ Φ d ι-H φ Φ 4-J SH EH 53 SH J cd iH -H

Di rH Φ ri -μ EH Φ SH d Φ -H 4-1 tn tn Φ Φ 1 dddd _* xi 73 d rH 5 SH -H • HN SH Φ -H> to a 4-1 rH 73 73 a Φ SH IM 53 4- ⁾ CM υ Φ d Φ a Φ Φ a CO Φ 73 Φ H in -H o 4-1 d Φ d 4-1 Φ rH o cd Φ

SH 4-1 SH co A4 5 o »- 73 co SH cd Φ a m Xl Φ 4H a 4-1 cd cq Φ SH: cd rH 53 ü

Φ to Φ U> cd N d tn Φ EH SH υ to d XI Φ 73 d 4-> Φ XI 1 O tn 4-1 73 φ Φ CM a SH d O d 73 XI φ d • H Φ cd Φ o Xl cd to 73 4-J tM a SH

: 0 J d SH rH Φ fi do> cd υ co> Φ 5H tn d ü -H d 4-1 d tM ad Φ 4-1 rH rH -H A4> tn dd cd 73 xi rH cd 4-> rH Di Φ Φ 4-1 1

SH d H D CO rH tu 4-1 d o cd d φ SH υ o Φ -H Φ SH rH SH d d φ rH

Φ XI d 1 Φ Φ Φ 73 tn tM> ^• H Φ cd rH co φ da: cd φ d + J d co rH

> υ • cd o rH 4-1 5H to 5H cd N Φ a 73 £ 53 to EH co XI d tn lo cd o CM 4H 00 rH to Φ -H -H to 4-1 SH -H Φ 1 Φ φ d 4- ⁾ xl cd υ 4H φ ü

4-1 O a 1 φ CO d φ 5 Φ Φ Φ to d d P a rH SH a • rH SH d Ü SH -H Φ • H

^• H φ κ-A as 4-1 tn S Di 53 4J ^• rH cd dd rH 73 O Φ Φ -rH 4-1 SH rH 73 SH a -rH Φ Ö to d. , o CD Φ d φ rH 4-1 Φ> iH 73 φ SH XI φ Φ

73 IM CM to d r- \ XI O 5H Φ a SH a H Φ 4-1 1 Φ 4-1 N φ u EH 4-1 d

4-1 d tn rH cd u H Φ -H o -H d φ o 10 PM d g tn Xl φ

^ o ä cd Φ ^• H

-μ Φ Φ SH d 4-1 4-J -H d 73 rH 2 φ d> H to M Φ g d υ PQ 53 a J Φ

• rH to d 4-1 Φ d 4-J -H Φ J cd • rH xl • H Φ Φ tn 4-1 p cd -H 1 -H 5H

Φ -H d Φ d rH -H tn rH -H d XI W u φ d d Φ cd d 4H SH φ Φ a O 4-1

£ o A4 -H 4-1 a • HD Φ Φ O -μ to E] • H ddd 4-1 tn -H & Xl d • rH d P ^■ 5 ^• H to CD 4H cd Φ 4-1 5H -öl xi 4-J Φ ^• H 73 φ Φ rH ^• H xi SH ri o φ a ü -H 73 4-J d 4-J aa -H φ φ d co in ddd 4-J Φ υ O ω cd Φ Φ rH d φ rH rH dda>a> -H Φ d N d rH 4-1 4-1 cd CM 53 SH O EH cd 4-1

^• H φ Φ Φ 54 Φ Φ 4-1 cd d ^• H -H tn -H 4-1 SH d 1 SH: d Φ O a 4-1 EH 4-J rH φ φ 4-1 4- ⁾ CO 5H P d 4H do φ daa Φ Φ a Φ 4H Φ to X) Xl co -H cd: cd> XI to CO tn Φ d Φ cd d H φ 5H: cd O d 73 dd ^• H SH υ

^• H Φ a P d U -H dd • xl X) Λ H IM Φ Xl ^• -H 4-1 O Φ P Φ CM: cd

Φ XI φ cd φ ^• C0 | cd Φ CM • 4H EH d SH>4-> SH Φ 5H Φ -H ö CM did 73 d A4 d rH rH O tn 4-1 LO Φ 4-1 4-1 d φ Φ d φ: d co SH 73 • _ d

• H -H 4-1 ^• H g xi rH d O SH d Φ cd d Φ Φ 73 4-1 4H Φ d Φ 4-1 tM

• Φ d -H Φ g: cd rH IM Φ 4-1 Φ SH do φ φ o -rH O φ d, dd • H l to dd Φ: 0 iS | N tn • rH SH Φ xl tn g to o 73 4-1 tn • H d ^• -HX! d cd • -i Φ 00

• Di d Φ CO d A4 Φ 4-1 Φ Xl 4H υ d rj o rH X! d Φ P ü Φ A4 -H Xl CM dd 73 cd SH CO A4 Φ co i φ -μ -rH d Φ od υ cd a 73 -H 4-J φ d 00 cd co SH d Φ φ υ 53 P dad Φ dd rH -i cd -H 4H Φ • Φ SH d • H •

* ». tn o Φ -rH. -. XI XI φ cd • rH Φ N d rH Xl .. cd 5H & 73 Φ 4-J tM cd Φ Φ wd • d rH S du rH Φ Φ to Φ - <- \ -rH υ 4-1 d φ XI a SH -.HX! Φ to 73 to 54 φ to tM do Φ to 4-1 -H o rH rH O XI) φ o SH -H -rH ü W Φ 73 ^• H XI D SH Φ Φ rH ia N 4-1 CD d -rH d • HOP rH φ rH rH SH EH φ la 73 cd cq tn co d φ dd rH

90 m cd 4-1 φ O d 4-J -H d 1 d cd 4-1 Φ tn ^• • d SH 53 gd _* . d tn d 5 Φ oo Φ d ri d Φ oo • φ φ 4H φ -H> dd 4H Φ 1 pd cd d 5H 5H 4-J A4

4-J LO 53 4J rH iH 00 SH rH 4-1 d rH Φ φ cd Φ EH 00 a N Φ d φ 4-1 Φ CO O

SH CM φ 4-J A4 d • 4-1 1 Φ rH CO φ rH X! a 73 tn CM d • -μ 4-J SH • H rH g 4-J rN Φ Φ 4-1 ^• H υ d PQ A4 g 4-1 Φ 1 d φ d -H d CM CO CO 00 4-1 O 4-1 rH 5H Φ d Xi g Φ O

XI cd -H

O d Φ cd o Φ ö Φ 4-J PM φ 4-> -H φ Φ rH d cd • Φ O to cd 0 -H 0: cd p ^• H

: SPH XI a S tM H PM s to H Λ t ω CQ tM rH cd PK co rH ^• H Xl PM 73 o £ d P PM

LO O LO O LO o LO rH rH CM CM 00 00

LO LO o LO O LO rH rH CM CM 00 00

Connection parameters via the internal signaling protocol to the TRUNK unit 50.

In the meantime, the TRUNK unit 50 has generated an IÄ message in accordance with the ISUP protocol and transmitted it to the exchange 112 via an inter-office line 114. The IÄM message contained, among other things, the telephone number of the subscriber TlnD and an identifier for the determined time slot.

The IÄM message is processed in the exchange 112 in accordance with the protocol. An ACM message (Address Complete Message) sent by the switching center 112 to the switching center 10 signals that the traffic control to the subscriber TlnD. Could be carried out completely by the switching center 112. The subscriber TlnD is now called, for example by a ring tone on his telephone. The ACM message is processed in the TRUNK unit 50 in accordance with the protocol. An internal signaling message is sent to the sub-connection unit 56, in which the receipt of the ACM message is communicated. The partial connection unit 56 signals the receipt of the ACM message to the IP control unit 22 with the aid of an internal signaling message. The IP control unit 22 then generates the alerting message in accordance with protocol H.323 and sends it to the terminal 100.

After the subscriber TlnD has accepted the call, the switching center 112 generates an ANM message (Answer Message) and sends it to the switching center 10. The TRUNK unit 50 receives this message and then generates an internal message which is forwarded to the sub-connection unit 56 and signals the arrival of the ANM message. The internal message also contains the connection parameters sent by the network access unit 106. The sub-connection unit 56 routes the connection packets contained in the internal signaling message. parameters to the IP control unit 22. An internal signaling message is used which corresponds to the subscriber signaling message “Connect of the DSS1 standard. After receiving this internal signaling message, the IP control unit 22 generates a connect message in accordance with protocol H.323 and sends it to the terminal 100. The connect message also contains the connection parameters that have been sent by the network access unit 106.

The terminal 100 is thus able to transmit voice data from the subscriber TnnC to the network access unit 106 via the Internet 108 in accordance with the RTP (Real Time Protocol) protocol. In the opposite direction, the network access unit is able, on the basis of the connection parameters received from the terminal 100, to transmit voice data coming from the subscriber TlnD via the Internet 108 to the terminal 100 according to the RTP protocol. In the network access unit 106, the port number was permanently assigned to the time slot on the PCM-30 link 110, so that the user data can be converted with a fixed assignment. In the switching center 112, the time slot defined by the switching center 10 is used for the transmission.

In another exemplary embodiment, the network access unit 106 is located in the switching center 10, see the network access unit 116 shown in dashed lines. The network access unit 116 can then be controlled via the internal signaling protocol of the switching center 10. The user data are then transmitted between the switching centers 10 and the switching center 112 via the intermediate line 114.

In FIG. 2, the functional units of the switching center 10 are also assigned to the so-called half-call model 120. An H.323 half call 122 is processed by the switching center 10 to the calling subscriber TlnC *. To the side of the called Attendee TlnD, the switching center 10 processes an ISUP half call 124. The two half calls 122 and 124 can be connected to one another by the internal signaling protocol 126 of the switching center 10.

The connection unit 20 performs the functions of the H.323 half call 122 and forms a first protocol converter on the periphery of the switching center 10. The connection unit 22 performs the functions of the half call 124 and forms a further protocol converter on the periphery of the switching center 10. The functions of the internal The signaling protocol is provided with the aid of the internal signaling messages, with the aid of the switching network 26 and with the aid of the central processor 26. The half-call model 120 has proven to be very advantageous when concatenating exchanges. This chaining can now also be used for switching data transfers in data packets. Such linkages are shown below with reference to FIGS. 4 and 5.

FIG. 3 shows functional units of the switching center 10 in the case of conventional interoffice signaling and segmental data transmission via the telephone network 102, the Internet 108 and the telephone network 102. The right part of FIG. 3 shows the functional units already explained with reference to FIG. 2. It is assumed that this time a subscriber TlnE who is connected to an exchange 150 of the telephone network 102 wants to reach the subscriber TlnD.

The switching center 150 is connected to the switching center 10 via an inter-office line 152. The intermediate exchange line 152 is connected to the connection unit 18, so that signaling messages are exchanged between the exchange 10 and the exchange 150 on the intermediate exchange line 152 in accordance with the ISUP protocol. In the exchange 150 or just a few meters or kilometers away from this exchange 150, a network access 1 co P ddol 1 to rH 1 d cd cd d 1

CD tn dd to co d φ -H 1 1 Φ rH 1 d Φ • iH in LO d N tM 4-J • o cd 4-1 rH Φ s SH d -H 1 ΓM Φ D dd SH o 73 xi Φ m in rH cd N IM -H 73 rH -H rH Φ: cd 73 1 2 4-1 dd Φ Φ Φ> SH rN Di 4-J 4-1 φ do Φ Φ ^• H ö rH o to J3j -H • H d 4-1 4-1 d Φ 73 o Φ d Φ Φ SH ^• H 4-J rH Xl 4-1 Φ in jl 54 d 00 SH H rH Φ 5H φ φ 5 ä o A4 N 53 53 φ C Φ d to PQ Φ φ Φ cd 1 Φ Xi Φ dg 4-1 φ • -. υ tM X) d Φ -H t 73 d £ {H. φ υ PM 73 xl -H to d 4-1 5H da φ -μ φ Φ d 5H rH Φ D • rH d -μ o rj -H co o 5H υ 4-1 ^• H l Φ Φ

ΪH Φ -H -H φ Φ φ rH CO d X! co -H φ Xl PM Φ 73 4-1 CD O -H to SH Φ ü 4-J i

H -μ 53 d P -rH 73 4-J Φ O d Φ LO Φ 73 υ d -rH 4H Φ Φ φ U £ -H Φ υ α. co 73 SH d 4-J d H ^• H rH rH d -H SH rH -μ φ s tM Xl dd SH

Φ 4-1 a -H

1 o H to rH 4-1 SH φ SH Φ -rH φ t J rH Φ ^• HHX! cd Φ o -H to d 2 to Xl 4-J 4-1 4-J a tn XI 73 φ 4-1 rH X) a Φ o 5H CM

00 73 ^• H Φ d to ^ υ • H Φ -H Φ rH υ EH -H d O Φ Φ • cd cd d

1 73 φ 4-1 cd d to a PQ φ 73 O cd N φ Φ A4 -H ddd 4-1 dads 73 Φ dd SH 73 ds SH Xl | ι 53 4-J CO XI d O 73 Φ ^• H o Φ 4-1 o Φ t_> d 4-1 do Φ rH φ ddd 1 -H Φ SH 4-1 73 Φ J SH tn A4

CM d ^• HX) • H 4-J SH 4-J> φ -H φ a Jgl rH 73 cd SH O SH -rH O d CO

Φ SH -μ d Φ 4-J rH tn Φ Xl -H S Xl φ: d SH Φ d 73 Φ S d tn

Φ o CO Φ A4: cd X! -rH Φ 5H ^• H SH υ H u XI 4H CM d 4-1 d (H XI 4-1 ddd LO> d rH: da 73 Φ 4-> φ tO Φ to Φ O d -rH 5H dd

-H rH dd SH SH 73 cd d -H -H H 4-> g co d cq d -rH 5 cd JS ^• H rH

Φ φ co 4H φ Xl Φ 4-1 d φ ■ ^■ £ 73 _* d -H g rH Φ: cd ^• H Φ φ X! φ

Φ 5H o to ü> C0 5H o 4-J d IM 4-1 -H Φ p xi a d to 4-1 XI d SH -H

SH rA Φ rH tn CD -H ^• H Φ ddo to SH da CO Φ d SH Φ Kl d 4-1 u Φ Φ O Xl Φ Φ 73

Φ rH SH 1 d tn Φ Xl 4H -rH ^• H i. -. 4-J Φ U ^< 3 * 4-1> O d Φ d 4-J d rH Φ CO cd xl PM 73 d 73: d J dd φ φ d rH 5H -rH LO tn U

4-1 cd Φ rH 4-J 73 LO 73 Φ H SH d SH 4H Φ ^• H rt XI IM J o cd 73 iH rH ddd to d 73 4-1 to rH to aod Φ Φ 73 Φ dd tn ^• H xi cd Xl Φ Φ 73 cxi o SH d -H to 00 X! Φ dd ^• £ tn d Φ -H dd 4-1 4-1 4-1 u -μ tM 4-1 d tn φ φ cd Φ: cti LO 4-> Φ d -H IM -H to Φ SH -H φ Φ Φ ü d φ cd -H SH Φ dd 73 4-J £ Xl H rH • rH ^• H φ 73 XI P d CO φ 73 CO «tM Φ φ d 53 Φ Φ

4- ⁾ dd

H ad Φ 5H d Φ SH d cd d C0 5H d 5π Xl ^■ 3

Φ rH 4H p -H - ^ 4-J Xl 4-J -H Xl to Φ rH O dd 10 φ d <* φ Φ d • = ^ SH Φ d 4-1 d Φ CM -H d Φ Φ U ^• H i> EH Φ LO dd rH cd • o LO 4-1 co -H LO O a

73 4-J <; a φ t rH Φ ^• H PQ -H Φ Xl 4-J rH -H d Xl d co co o rH d Φ Φ rH Φ g

SH -H Φ -H Di l Φ SH CO £ υ -t 4J u LO LO H • H co tn poa • 73 73 d 4-1 d SH d: d rH cd Φ -H Φ 4-1 to -μ rH rH Φ 4-1 P tn 4-J dd

Φ π 4-> cd -H -H Φ Φ 4H 4-1 XI SH g SH rH o φ ä XI 4-1 -H 54 d -H tM 4- ⁾

Di φ Φ 4-1 4-> D Φ Φ d SH CO cd ar] l r- \ rH d -H 4-J 4-1 cd Φ Φ • cd Φ SH d> 73 -H cd d Xl SH Φ Φ • CO 5 co Φ o Φ xl tn -H -H φ X! dd tn i NO cd da XI tM d Φ 4-1 tn PQ: cd dt 4-1 Φ υ φ SH Φ Φ SH d -H Φ dd 4-1 CM φ ^• H IM -H d CO d rH co SH rH co CO rH -H -H Φ Xl Xl O -H Φ 73 IM • rH -H

"^ -rH X)" T "= J <-μ Φ Φ 1: cd tM rH Φ -H d O rH Φ P XI d d - 'Φ d tM φ r-H

LO 73 SH LO LO Φ to 4-> PM H φ d φ φ tn Φ IM: d -H ^• H CO 4-1 ^• H 4-1 to Xl Φ rH Φ rH rH 53 tn OH _. > 4-1 -H EH SH d 4-1 Φ • Φ Φ 4-1 D • H XI Φ tn u to

Φ> d 1 SH 4-1 ^• H • rH φ xl d CO X! -μ d 5H SH Xi d iH 53 d to to

4-1 X! 4-1 4-1 φ cd CM Φ Φ Φ 4-1 φ cd a

^• H dd cd xl da rH CO O d Φ Φ υ cd Φ cd 4-1 φ

-H υ • vT -H -H -H tn M φ 4H 4-1 tn CD -H d d d -H Di tM> SH tn -rH in

Φ rH LO Φ Φ 73 d P • H 73 dd cd 73 5H 4- ⁾ d Ul Φ Φ rH d 4-1 Φ d φ 73 xl φ rH xl Xl N SH φ SH ^• HX) Φ -H d rH d 4 -1 4-1 4-J XI N ^• H d 73 N ti cd d ^• £ dd ΪH CM Φ. o φ Φ 4H 73> a H Φ xl co co υ IM rH N tM 4-1

90 in -H 4-1 -H ^• H: d 4-J dd 73 φ 4-J to dd SH 4-1 Φ X! u 1 1 cd 4-> Xl -μ 4-1 rH to a φ f Φ ^• H Φ Φ 4H Φ -H SH d tn rtj dd Φ 4-> A4 Φ -rH PM PM 53 Φ υ X -H Φ φ dd H to 4-J φ co C0 53 Φ Φ φ d PÜ d Φ> -H ü D SH HH 1 53 CO Φ 55 73 D

_^ tn 54 xi Di tn dd SH tM rH a ω 4-1 a φ Φ Xi X 4-1 4-J Xl φ D cN

O d XI d d d φ φ d Φ Xl SH Xl -H d SH Φ SH SH tn υ Φ Φ C Φ • H 5H d SH Φ 4-J cd

O cd: d -H cd cd X! -H o 4-1: cd σ Φ υ Φ rH Φ -H Φ 4-1 d cd -H • rH d -H Φ O ^• H φ -H d 5H tn 4H Φ tn tn OP i> co 2 rH d to PQ EH 4-1 P> co cd 53 73 P ud IS] CM Φ 73 73 H 4-1

LO o LO o LO o LO rH κ-i CM CM 00 00

1

X u

P s μ

Φ d

-H

Φ

4H rH

-H iH

4-1

-H a

00

LO rH

4-J

-H

Φ

Xl d

•H

Φ μ

Φ d

Φ

4-1

CO

1

CM μι

Φ

•H

73 μ φ

X)

:

4-1 μ

0

73

LO o LO o LO o LO rH rH CM CM 00 00

Transfer message (Modify Connection) to the gateway unit 154. This takes place simultaneously with or independently of the implementation of an ACM message coming from the exchange 112. Further signaling takes place in accordance with the ISUP protocol. If the subscriber TlnD accepts the call, the voice data between the subscribers TlnD and TlnE are transmitted via the PCM-30 link 156, the Internet 108 and the PCM-30 link 110 or in the opposite direction. The switching center 10 thus controls in the middle part of the connection, i.e. on the Internet 108, a so-called backbone network.

A half call model 160 shows which functional units of the switching center 10 are assigned to an ISUP half call 162 and the half call 124. The two half-calls 162 and 124 are again linked via the internal signaling protocol 126 of the switching center 10. The functions of the half-call 162 are provided by the connection unit 18 and the IP control unit 158.

FIG. 4 shows functional units of the switching center 10 and a switching center 200, which belong to different operators. The functional units shown in FIG. 4 are used to mediate a transmission of voice data, which is carried out in marginal sections via the telephone network 102 and in an intermediate section via the Internet 108. It is assumed that the subscriber TlnE connected to the switching center 150 wishes to speak to a subscriber TlnF who is connected to a switching center 202 which belongs to the same operator as the switching center 200.

The functional units shown in the left third of FIG. 4 correspond to the functional units explained with reference to FIG. 3. For the signaling with the switching center 200, a connection unit 204 is used in the switching center 10, which signals to the outside in accordance with a supplemented ISUP protocol. Signaling towards the inside based on the internal signaling protocol. The extension of the ISUP protocol is that information elements can be sent from the connection unit 204 to a connection unit 206 in the switching center 200, in which connection data relating to the data transmission within the Internet 108 are contained. These connection data include Internet addresses, port addresses, coding type identifiers, etc. The connection units 204 and 206 and thus also the switching centers 10 and 200 are connected to one another via an inter-office line 208.

The exchange 200 is constructed essentially like the exchange 10. It contains a central processor 210 and a switching network 212. The functions of the central processor 210 and the switching network 212 correspond to the functions explained with reference to FIG. 1 for the central processor 26 and the main switching matrix 24. The structure and function of a connection unit 214 corresponds to that of the connection unit 20. The connection unit 214 contains one

TRUNK unit 216 and an IP control unit 218. The exchange 200 is connected to the exchange 202 via an inter-office line 220.

The IP control unit 218 is used to control a gateway unit 222, which is set up as a remote unit in the exchange 202 or in the vicinity of this exchange. The gateway unit 222 can receive data packets with voice data sent by the gateway unit 154 or send data packets with voice data to the gateway unit 154. The gateway unit 222 is also connected to the exchange 202 via a PCM-30 link (pulse code modulation).

When establishing a voice connection between the participant

TlnE and the subscriber TlnF are first carried out the method steps explained above with reference to FIG. 3. The 1 4-1 1 1 1 a 1 Φ 1 rH CO 1 φ μ 1 μ 4-J 4-1 φ 1 Xl 1 rH φ d μ 1 • H ^• H μ -H Φ dd cd μ dd £ jd φ 73 « cd CM CD ^• H rH -H Φ -H

ITi to d d Φ Φ 73> H Φ Φ Φ Φ Φ g μ Φ • H μ 1 525 4H LO 0 Φ Φ 73 -H φ

IT! Φ IM 4-> -H EH N 4-1 dd Xi gdti ^• H -H dd Φ CO 5 d μ rH X! 4-J 73 ofo 73 φ Φ 4-1 d -μ Φ μ Φ a μ 4-1 £ μ cq tn tu cd Φ 4-J o to a φ to

Di 73 10 CO ^• HH rH 73 d • H μ. 73 p Φ d CO 1 Φ CD dd EH> -H 4- ⁾ Di co Φ d -H d μ ddt φ H: rd N 73: d ^ dd 4-J Φ Φ ds 4-1 σ <dd Φ ^• H d D 73 cd 73 rH ω Φ d φ d 73 Xi to 1 XI 4-1 4H LO d 4H dd X! -H d CM rH Φ Φ d Xl Φ ddl X!

Q ö a 73 to rH U cd CM 4-1 -H • rH d -H xi -H • 4-J -H d Φ d X! μ d u d μ 0 d l μ co 73 P d g LO

H PQ -μ 4-1 Pi Ö o 4H d 4-> μ -μ P 4-J -H d XI rH cd Φ Φ co p -H ^ PU υ Φ 4-JO Φ Kt μ 4-J xi μ cd rH d φ Φ • H Φ -H Φ μ Φ -H: d 4-1 53 4-1 XI α. d XI O CO g ^• H μ IH 4-1 IM cd -H u Φ Φ CM cd 73 to Φ 4-1 -1 cd: m μ CM g Φ Φ dd 4-1 CO Φ -H • H d CM μ Φ l ^• H a • -H Φ μ Φ 4H 4 μ 4-1 3 4-1 Φ O o -H • 73 d Φ s

% p t J X! a Φ φ • H • tn XI μ d -H rH μ cd d -H d Φ Φ μ dd tn dad co φ φ ffi> 4-1 d = d -H 4-1 a Φ Xl dd xl Φ CM o P φ 73 -HS> Φ. : cti Φ d PH μ Φ Di co -H to -H Φ 4H dd Φ Xi d -H ud to Xl Φ • H co rH 4-> cd Φ D d φ 73 μ D Φ -H d Φ dd Φ rH dd 'μ Φ rd μ Φ IM O • o μ CO CD μ to d μ CO tn d O d -H

Φ d i d Pü d -H Φ a Φ -H Φ CO 53 • H 4H 4-1 Φ CD o Φ to rH Φ -H cd Φ 1 μ φ tM 73 73 d

73 dd ^• H XI 73 Φ CO Φ -H Di 1 SH Φ IM rH -HX! d CM d rH CM Φ 4-1 Φ φ d cd μ -H d Φ φ Φ rH d to ddd *>] ^• H do CM s: P rH cd Φ 0 H XI μ -H XI -H d

73 Φ Φ cd -H dd Φ o tn do cd ζ -HK rH μ IM Xl 4-1 dd -μ LO = d Φ 73 d X! φ CM d -H to 73 μ xl IM CO -H d -H u Di H Φ Φ a 4-1 • υ ^• H -H n 4-1 μ tM 4-J ^• H μ 73 rH d co CO -μ ^; o ri 4-1 cd to d X) 4-1 a rH -HD 4- ⁾ CO Φ • H -H 4-1 Φ 4-1 d Φ Φ μ CM μ -H d Xl 4-1 4H Xl 0 cd tn Φ tM φ cd ^• H a cd Φ dd ä XI 4-1 to μ • H 73 Φ: cd CO!> φ tn H rH υ td υ ^• H add -HN -HP ao μ Xl d cd d Xl xl Φ 53 rH rH CM 5 IM

4H cd l -H -H Φ Φ -H 4-1 μ IM Φ d -μ d «4-1 dd XI ^• H ü CD u Xl Φ μ CM CM co 4-1 dd υ μ XI 4-J rH cd 0 IM d Φ _• 73 d • H d Φ Φ φ • H rH to d rH μ Φ CM 4-1 Φ cd tn co xl 4-J cd cd N a 4H 4-J μ d Ϊ3 4-1 PM d to Φ Φ -H tn • μ CO μ CM O -H rH Φ 4-> -H 4-> d

-H υ ä Xl tn d 4-> μ d Φ o d tn P d cd t i O X) 4H 73 to XI d H Φ d μ -H 4-1 Φ cd rH

LO j O cd U rl J s IM: cd o H 53 sd μ do 73 CO μ ddu 4-1 Φ 1 4-> d Φ ^• H co Xl Φ

53 -H 4-1 to 4H Φ: cd H d μ d Φ cd 4-J .H cd -H μ «CO d tn l Φ μ

0 Φ φ 1 μ d d d d μ d μ 73 4H Φ μ Φ H> X! xi 53 Φ xl g -H d Xl Φ 4-J o Di rH tn O s d 4H pci a d

73 d -H s xl φ 53 t J H -H Φ Φ Φ a rH g Φ P XI to CD • H υ 1 Xl cd 5 d h -H d μ φ 0

Φ μ P tj υ d Φ d Di g d a r- \ g X) Φ -H Xl 73 id

-1—1 Φ H cd -H Φ • d cd g ^• H φ O o: d ■ or CM

-H d d g. 73 Φ o s tj -H μ EH »CM μ μ Φ -H d

4-J • 53 w -H d φ Xi d μ A4 d 4-1 d 1> Φ φ rH d d tn CM co cd d> μ 4-J Φ o 4-1 d X! d ä d tn H w Φ d rH Φ Φ to φ o

4-> d 4H Φ 1 d Φ d u o 4-1 d d CD o 4-J 4-1 Φ μ d

Φ dd Φ μ fctf -H Xl Φ d CM φ 73 cd cd • H ^ H d cd μ XI d Φ μ 4-1 CM o Φ ü d φ -H d 73 • H Φ £ 5 dd υ Φ 73 -μ cd CM tn

Λ Φ Φ H Φ d Φ Φ Φ X! o φ μ -H Φ -H to dd 73 5 d Φ rH d O tn 73 d P 4-1 S -H xi -H • ^• d PM A4 4-J PM Pm μ to d -H CD -H et; cd μ μ rH cd 1 μ -μ <d co • HO cq μ rH μ u 73 d -H d xl Φ rH OX! dd EH 73 ^; d fi CM Φ -H rH d rH a Φ f

Φ CM: cd Φ rd xl d l o o Φ a Φ cQ rH u tn IM cd CM μ cd Φ 4H to 4-1 H Φ CM a o X! u Φ Ü d rH -H d Xl: cti EH cd d d Φ 4H Φ 4-1 4-1 O d XI CD

4-1 (x, 4-J φ φ 4-1 -H tn to Φ d d Φ d a d o rd oil d> d 4H -H μ 00 d o cd Φ N d 4-J r-i

-H d -H D> -H d rH cd φ ^• n Φ Φ 4-J ^• H Φ to co rH -μ ^• H φ o φ Φ 73 xl Φ tn -H 4-1 -H ^• H CM

Φ rH Φ rH 73 φ μ μ Di 4-1 rH cd Φ Di μ oil CM tO CO 4-1 tn -μ μ: d μ d a 73 Φ Φ φ

Xl EH Xl rH Φ 4- ⁾ μ 4-J cd ri φ P co Φ dd -H d cd 4-J d 4H ddd Φ 55 to Xl 4-1 dd O d tu d μ o xi 73 Φ to CO Φ d μ • H Φ Φ ddd cd D Φ rH Xl D d ^• H

-H CO -H A4 H d μ Φ> υ to 4-J to dd O jq μ o μ d xi μ o • H CD ^• H 4-1 4-1 Ü Φ d ^• H Φ

Φ μ Φ O rH 0 XI ^• H oil CO φ 0 rH Φ Φ Φ to Φ μ d Φ tn C i 0 rH lχι 4-J 4-1 -HO -H cd φ xi to φ t 4-1 • EH 4H : d rH μ d 10 μ> X! -H d • H co d Φ -H -H d 0 CM ^• H ^• H Φ 73 73 Di μ d to j OOO μ rH xl d tn d υ d rH co φ 4-J 4->

9 © Φ od co CM μ μ a XI Φ μ φ -H d _r id d μ O CO Φ 00 oudd cd tn CO ^• H -H tM μ d to -H 73 cd 4-1 Φ xl μ ^• nd Φ df rH w φ rH a CM μ o A4 rd dd 4-1 d 4-1 Φ rH o rd -H CO rH dd Φ -H 73 u Φ dd XI Φ 1

Xl d Xl 1 Φ 4-1 rH O 53 -H rH Φ cd Φ EH rd μ PM d cd -H rH Φ to> Φ rH d: 4-1 υ CM w 5 o rH 4-J xl -μ 1 X ! 4-1 d 4H -μ da φ rH d X) d rH XI d to d Φ tM oo 10 • H CO P • H υ 4-1 O Jgj μ 4-1 μ a Φ -H CO tn r- co d Xl Di μ μ Φ ddd μ μ • H CM -μ 1 | 3 φ co Φ

O φ -H Φ μ

£ s ζ Φ -H Φ g -H Φ φ • H cd rH -H υ -H Φ • H 4-J -H cd Φ Φ Φ a O Φ CM PH

EH H Xl ddd PM IH> a 4-JWP XI 73 o μ cd Φ 10 to> OI ^χ 1 ω μ d 3 = to CM 53 IH

LO O LO o LO 0 LO rH rH CM 00 00

unit 206 passed on. The connection data is transmitted to the connection unit 204 with the aid of an APM message. The APM message is specified in the ISUP standard. Information elements are transmitted in the APM message which contain the Internet address, the port number and the type of coding which are to be used for the connection between the subscriber TlnE and the subscriber TlnF.

The connection unit 204 reads the connection data and sends it via an internal signaling message to the connection unit 18. In the connection unit 18, the connection data are transmitted to the IP control unit 158 and from there to the network access unit 154.

If the participant lifts TlnF, then ANM

Transmit messages between switches 202, 200, 10 and 150. Thereafter, voice data from the subscriber TlnE via the switching center 150, the PCM-30 link 156, the gateway unit 154, the Internet 108, the gateway unit 222, the PCM-30 link 224 and the switching center 202 become the subscriber TlnF or vice versa Transfer direction.

In another exemplary embodiment, the connection unit 204 is assigned an IP control unit 226. An IP control unit 228 is assigned to the connection unit 206. Instead of the intermediate line 208, the Internet 108 is used to transmit the messages in accordance with the supplemented ISUP protocol.

FIG. 4 also shows two half-call models 300 and 302. The half-call model 300 relates to the switching center 10. The half-call 162 to the subscriber TlnE is implemented by the connection unit 18 and the IP control unit 158. An ISUP + call 304 exists to the subscriber TlnF. The functions of the ISUP + half call 304 are performed by the connection unit 204 or by the connection unit 204 and Φ XI a 1 1 1 1 d. 1

CM H CD -H o φ d -H 1 μ 1 to φ CM cd 1 1

CD d OP 1 μ O 73 -H Φ 1 rd Φ μ to tn 1 CM d μ 1 mddm rH CD rH h 00 dd 1 rH φ Xl μ 4H d 1> Φ dd CM co Φ md to dd 1 Φ d tn rN o rH rH CO 1 4-1 Φ tn d φ d cd -H d 73 rd -H a rH cd tn ^■ 5 C0 d -H 4-J

Φ d cq XI rH a 4-J d a Φ 1 4-> Φ

CM EH d -H d CO

-H Φ cd

4H CO EH Φ o ω a Xi CO XI d φ XI o Φ tM o Φ: rd υ φ μ -H dd μ ^< XI Xl dd rH μ 4H υ CO ud r- υ -H d O 73 CD Φ d φ O a co Di d Φ d Φ do μ d co μ rH ad cd d ^• H rH rH to 4-J Φ d 4-1 d LO Φ ^• H d Φ Q μ μ φ μ rH to 4-J φ -H A4 XI o Di cd d P Φ tn S, tM XI d -μ tM CM φ -H tn

XI O CO d -H cd> Φ d H rH A4 _d Φ XI -H XI xi 4-J 4-1 £ do -H rH K -μ μ ö d CM -H XI d to 4-1 O d U cd O Φ Ö • -H 73 μ U d -H to tM d 4-1 o -H Φ • g CO Φ cd rH Φ μ co • H -H d O 73 α. K -μ • d rj cd Φ CO Φ a co [ ^χ ι d A4 4H d Φ -μ 4H oo -H CM co Φ tn X) Φ Φ dd

O μ rH Φ K XI 10 μ oil tn Φ d

£ d μ cd Xl dd A4 CM d D tn> Xl 73 rH ^• H d μ cd -H d υ 00 to φ dd. 73 d Φ d ^• H cd o IM dddd Xl XI

Φ a X! φ rH co μ CM cd> dddhd -H o tn d CM 4-1 cd o 73 4-1 ^• H Φ u μ d O 73 EH • H Φ d CM φ rH rH d Φ dd Φ φ φ "P od cd Φ tn 4-1 d μ Φ ö to Φ

-H tn d Φ 73 73 -H μ -μ dd Φ d cd XI co do rH d 4-1 d μ -H ^• H Φ CO g

Φ a> d -H to EH 4-1 73 co Φ 4-1 ^• H Φ xl Φ X) o co ^• H CM 4-1 4-1 -H rH Φ Φ XI 4-1 CO o

X! d XI φ d. -H o 73 -H X) -H o 4-1 4H d Φ rH -H xl Φ φ X! CO μ d d A4 Φ μ μ 73 C0 φ 5 φ Xl 00 a μ d Φ μ d Φ rH -μ cd Φ υ Xl a: d μ Φ: cd r-i φ -H

Φ Φ Φ Φ d N Xl Ü O μ Φ μ Φ cd -H XI fxi -H d r- -H d a tM Φ> r-H Xi CM • H 73

^• H -H> Φ do XI d μ d rH φ> [ ^χ ι a 4-1 to 5 ud Φ -H CO μ -H o 4-J μ μ V CM d

P co 4-1 -H -H d d 00> d co d tn o rH xi X Φ xl Φ Φ CO

-H μ -H Φ 4-1 CD φ 73 d μ -H 4-1: cd d o a 4-1 xl Φ CM d a EH d μ

• a O CO 53 -H co ad φ rH Φ Φ 4-J A4 O μ rH μ Φ EH d rH d to ^• H Φ cd cd OO Φ <= + J cd 73

4-1 dd CO ^• H d 00 Φ d CD rH φ d Φ μ d co Φ EH d 53 d cd μ -μ -H -H μ μ dd Φ dd Φ OO 73 • H μ φ d φ μ CO φ 1 rH dd Φ P μ Φ Φ <Φ

Φ tn cd μ CO r ^χ ι 4-1 Φ 73 oo A4 Φ Φ d -H o -H Φ co tM dd -H Xl CM Ξ

-H -H dd ^• H 4-J μ odg Φ ^• vP XI odgda xl s XI

O υ Pζ υ μ d • tn P d CM to co ^• H tM μ Φ Φ CO Φ φ 4-J φ dr] xl μ rH, rH> to H CO Φ -μ Φ ^ P -H -H CD

CM -H Φ d ^• H XI 1 4H o 4-1 rH Φ u μ Φ 4-J Φ XI ^• H d μ to rH Cxi • Φ IM LO rH φ -μ 4-> MP d PM d μ -H Φ d • H d> rH dd ü Φ S μ S,: do CM d 10 4-1 cd d ^• HH ^• HH co μ a Φ 4-1 H Φ tn cd cd rH CO -H t J Φ 73 CM μ Φ Di Φ 4-1 φ μ a: cd 73 • Φ o XI to Xl 4-J -H tM -H gd XI ^• H i 73 d μ d CM 4-1 Φ tn dd ^• H μ Φ Xi d co co Φ 00 H oil d ^• H Φ thp • H Φ φ Φ dd CM -H 73 cd cd rH Φ

4-J o 4-J d o co -H cd d -H a EH tn IM Xl

CD d rH d 00 d 73 to m d φ μ d μ a EH 4-1 -H d 73 cd o Φ μ tn φ Xl μ υ μ Φ 73 -H 73> 4-1 XI 73 4-1 μ a d

CM -H Φ CD rH φ μ co Φ a N Φ tn Φ o co d -μ d -H d d μ φ a -H

CM Φ O 4H Xl 73 4H Φ Φ d> Φ Φ 73 d EH d φ tM -H μ <-H o d 73 Φ -H cd Φ X! O Φ

CO rH CM 00 d υ d d -H -H. o 73 PQ d Φ d φ Φ r-H> Φ d Xl Φ M XI: d ^ CO

4-1 rd rH O μ C0 d μ P CO d -H co d μ a P tn rH X) O 4-1 d d CO: d tM CO

-H 73 φ 00 4H XI a XI -H Φ 4-J cd d d d Φ o μ d: d A4 • cd -H co d 4-1 to d

Φ J d rH CD rH. rH d A4 dd φ d -H>. Φ d ^ PO μ 73 ^< sP Φ d cd "^ P Φ cd rH

Xl μ CO -H μ cd O cd 4-J cd d d d Xl co 4-1 g d o μ 4-1 Φ co rH co rH o 53 73 Xl d Φ to rH X! m Φ CM Hl XI d -H d μ ü CM -H d μ g d CM Φ O 4-J tn CM tn XI d CM υ

-H XI tn φ H 1 ^• H υ Öi X! h = do -H rH d Φ p -H 4-1 μ -H dd ü Φ μ μ O

Φ dd cd PM 73 J co cd -H μ 4H d φ μ cd Φ -μ d X) 4-1 Φ PM Φ d 4-1 cd O XI 4-1 Φ φ μ dom P -H φ μ CO Φ 4 -1 rH rH dd xl d 4H μ -H 1 5 d ^• H Di

Φ 73 rH a 1 co Xl Φ 73 XI> Di Φ H tn Öi a a o -H 73 X!

D Φ: cd d Φ Φ cd PM d Φ μ Φ: dadd 4-1 4H + H υ XI μ Φ -H -H ^• H -H tn rH PM ^" > xi μ P CD -H Xl Φ φ xi d μ

Φ -H 4-1 d PM μ dd Φ do φ d μ 4-1 C ^χ ι CO to μ co d cd co OX) d XI Φ -H dod Φ

4-1 O -H μ P dd -H φ μ o tM Φ ^• H d φ μ tn ^• H a H CM μ ^• H: d -H 5 -H> Φ d

CO

90 a X! o Φ d Φ d ^ Φ oo ö m a μ Φ cd Φ d Φ to Φ Φ N 73 Φ 4-1

1 ¹ μ rH H d CO o rH 4-1 LO o F] φ -H <M 73 d O tn a 4->> O 4-1 o O Φ cd d

CM O Φ cd -H d to -H CM d φ o Φ dd P 4-1 μ 10 d φ -HO Φ do CO ^• H 73 o

H 00> Cd d Φ Φ d -μ ^• H rH μ CM d φ 10 μ 73 Φ dd -μ Φ Φ d 53 cd dd 10> φ d H A4 4-1 rH d rH 4-1 73 • Xl dd - HH d IM Xl to rH rH tn

73 dd P Φ Xl £ to XI d CO l ^χ ι d EH Xl K 4-J df ^χ ι D rH to XI tn Φ d P 4-1 d C0 dd LO

L0 o LO o LO o LO rH rH CM CM 00 00

then sent to the terminal 100 via the IP control unit 58. If the subscriber TlnF lifts the handset, then according to the ISUP protocol, an ACM message first arrives at the exchange 200 and then at the exchange 10. After processing these messages, the subscribers TlnC and TlnF can use the Internet 108, the gateway unit 222, the PCM 30 route 224 and the exchange 202 exchange voice data.

In another exemplary embodiment, as explained above with reference to FIG. 4, the Internet 108 is used instead of the intermediate line 208 in order to transmit connection data from the terminal 100 to the gateway unit 222 or in the opposite direction. The Internet 108 is also used for signaling between the two switching centers 10 and 200.

A half-call model 350 contains the H.323 half-call 122 on the subscriber TlnC side and the half-call 304 on the subscriber TlnF side. The half-calls 122 and 304 can be connected to one another via the internal signaling protocol 126 of the switching center 10.

A half-call model 352 contains the half-call 306 on the subscriber TlnC side and the ISUP half-call 308 on the subscriber TlnF side. The half-calls 306 and 308 can be connected to one another via the internal signaling protocol 310 of the switching center 200.

In other exemplary embodiments, the subscribers TlnD to TlnF are connected to switching centers other than switching centers 112, 150 or 202. The exchanges 112, 150 and 202 are then transit exchanges. However, the signaling explained remains basically the same.

Although only the connection establishment phase has been explained with reference to FIGS. 1 to 5, similar signaling Operations also performed in the disconnect phase. The connections switched in the exchanges are retained between the two signaling phases.

In a next embodiment on the Internet, the protocol TCP (Transmission Control Protocol) is used for the transmission of fax data between the participants. This protocol does not ensure real-time transmission, but is suitable for the transmission of fax data.

Claims

claims

1. A method for switching for the transmission of user data packets, in which a signaling unit (10) contains at least three optionally connectable connection units (20, 22), which can be used when establishing a connection for the transmission of user data, the user data in data packets from the network nodes are forwarded to a network which transmits user data on the basis of data packets, the line units (20, 22) each complete the signaling to one of the terminals involved in the data transmission, and in which signaling messages arriving at a line unit (20) for the transmission of the Data packets can be forwarded to the other connection unit (22) with the aid of internal signaling messages (126) defined for the signaling unit (10).

2. Method for switching for the transmission of user data packets, in which a signaling unit (10) contains at least two connection units (20, 22), which can be used to set up a connection for the transmission of user data, the user data in data packets from the network nodes of a network forwarded, which transmits user data on the basis of data packets, the connection units (20, 22) each complete the signaling to one of the terminals involved in the data transmission in accordance with a signaling protocol for circuit-switched transmission of user data, and in which the connection unit (20) incoming signaling messages for the switching of the data packets can be forwarded to the other connection unit (22) with the aid of internal signaling messages (126) defined for the signaling unit (10).

3. The method according to claim 2, so that the connection units (20, 22) can optionally be connected to one another.

4. The method according to any one of the preceding claims, characterized in that the connection units (20, 22) via a switching network (24), which preferably transmits the internal signaling messages in channels, or a bus system or a data network can be connected.

5. The method according to any one of the preceding claims, characterized in that the connection of the connection units (20, 22) is controlled depending on the connection destination (TlnD).

6. The method according to any one of the preceding claims, characterized in that one or more signaling messages are used to transmit an information element which contains an address at which the terminal (100) or a gateway unit (124) on the side of the terminal data packets can receive, and / or which contains a port number, which designates a receiving unit of the terminal (100) or the network transmission unit (154), and / or which contains a coding identifier which, when sending data packets to the terminal (100) or to the gateway unit (154) denotes the type of coding used.

7. The method according to any one of the preceding claims, characterized in that further connection units (12 to 16) are used for switching user data in a circuit-switched network, and that the further connection units (12 to 16) have the same and / or similar internal signaling messages as that on establishing the connection for the transmission of user data in data Create and / or edit the connection units (18 to 22) involved in the ten packages.

8. The method according to any one of the preceding claims, d a - characterized in that at least one of the connection units (50) involved in establishing the connection works in accordance with the ISUP protocol or a protocol based thereon.

9. The method according to any one of the preceding claims, characterized in that at least one of the connection units (204, 206) involved in establishing the connection works externally in accordance with a supplemented ISUP protocol, at least one information element having been added to transmit an address is used, under which the one terminal (100) or a gateway unit (154) in the packet-switched network can receive data packets, and / or is used to transmit a port number that designates a receiving unit of a terminal device (100) or a gateway unit (106) , and / or which is used to transmit a coding identifier which designates the type of coding used when sending data packets to a terminal (100) or a gateway unit (106).

10. The method according to any one of the preceding claims, characterized in that at least one of the connection units (20, 22) involved in establishing the connection completes the signaling in accordance with a signaling protocol for a packet-transmitting data network.

11. The method according to claim 10, characterized in that the signaling protocol is a protocol for signaling with a terminal (100), preferably the protocol H.323 or the protocol SIP or Is the MGCP protocol or a protocol based on these protocols.

12. The method according to claim 10, characterized in that the signaling protocol transmits data packets on a lower protocol level and on an upper protocol level originally signaling messages defined for a circuit-switched transmission network.

13. The method according to any one of the preceding claims, characterized in that at least one of the connection units involved in establishing the connection includes a control unit in the switching process, with the aid of which a gateway unit (106) is included, and that in the gateway unit after the connection is established, the user data of the connection are extracted from time channels and distributed to data packets and / or user data of the connection is extracted from received data packets and forwarded in time channels.

14. The method according to claim 13, characterized in that the two connection units include different control units.

15. The method according to any one of the preceding claims, characterized in that a connection unit contains at least two sub-units that exchange internal signaling messages with each other.

16. The method as claimed in one of the preceding claims, characterized in that the user data are forwarded without a connection by the network nodes of the packet-transmitting network (108), preferably in accordance with the IP protocol, or that the user data of the packet-transmitting network are forwarded by the network nodes of this network in a connection-oriented manner, preferably in accordance with the ATM protocol.

17. Signaling unit (10) for switching for the transmission of user data packets, with at least two connection units (20, 22) which are used when establishing a connection for the transmission of user data in data packets, the connection units (20, 22) each signaling terminate one of the terminals (100, TlnD) involved in the data transmission, and a connection unit (20, 22) arriving signaling messages with the aid of internal signaling messages (126) defined for the signaling unit (10) to the other connection unit (22) forwards.

18. Signaling unit (10) according to claim 17, characterized in that the signaling unit (10) is constructed such that it carries out a method according to one of claims 1 to 16.

19. Switching center (10) for a circuit-switched network, characterized in that the switching center contains a signaling unit according to claim 17 or 18.

20. Program with instructions, in the execution of which a method according to one of claims 1 to 16 is carried out.