Abstract:
The present invention is directed toward, a data sink/data source data transmission device and data terminal device for a circuit-switched and packet-switched network, the ability to eliminate the logical separation between applications, which are based on the circuit-switched network (e.g., PSTN, ISDN), and applications, which are based on the packet-switched network, (e.g., Internet). To this end, a data transmission device for transmitting and receiving data into/from the circuit-switched network includes controllable switchover parts. This data transmission device is or can be assigned to a universally useable unit for automatically processing data and for transmitting and receiving data to/from the packet-switched network and is assigned or can be assigned to the at least one data terminal device for transmitting and receiving data into/from the circuit-switched network. The switch-over parts can be controlled in such a manner that the data terminal device which, in a first operating mode is connected to the circuit-switched device, can be switched from the first operating mode into a second operating mode, during which the data terminal device is connected to the packet-switched network via the data transmission device and the data processing device, and from the second operating mode into the first operating mode.

Description:
BACKGROUND OF THE INVENTION 
   Publications on the subject of “Home Networking” or the “Connected Home” or “Telephony and Control” talk about the networking of devices in the private field, such as, for example, TVs, personal computers and other devices in everyday life. In this connection, the telephone, fixed network telephone or cordless telephone, serves as the gateway to the circuit-switched network (voice network). Here, access to the packet-switched network (data network)—(e.g., Internet access) is insignificant, and can be effected in various ways. 
   The connection between the packet-switched and circuit-switched network, as shown in  FIG. 1 , only exists to the extent that devices, such as a personal computer which is connected to the packet-switched network, (e.g., the Internet), via an Ethernet, Digital Subscriber Line (DSL) or cable link, for the purpose of transmitting data in packets and, for example, a cordless base station which is connected to the circuit-switched network via an ISDN/PSTN network termination for the purpose of speech transmission, request that a connection be established (control), or to configure the device with the help of a cordless mobile module (configuration). In doing this, parts of the cordless base station or the telephone functionality are transferred to the personal computer. The control and configuration also can, of course, be effected in the opposite direction. 
   What is critical, however, is that no voice data is processed in the packet-switched network or data network, as applicable, but instead there is always a logical link between the voice terminal device, the cordless mobile module, and the switching center, the cordless base station. That is, there is no logical link between the circuit-switched voice network and the packet-switched data network (e.g., the Internet) in relation to voice data. The benefits of voice services in the packet-switched data network (such as, for example, Internet telephony, voice messages) are currently not utilized via a cordless mobile module registered with the cordless base station. 
   Accordingly, the present invention a data sink/data source, data transmission device and data terminal device for a circuit-switched and packet-switched network which eliminates the logical separation between applications which are based on a circuit-switched network, (e.g., PSTN, ISDN), and applications based on a packet-switched network, (e.g., the Internet). 
   SUMMARY OF THE INVENTION 
   The idea underlying the present invention is that a data transmission device for the sending and receiving of data, in particular voice and/or packet data, respectively into the circuit-switched network or out of the circuit-switched network, which is assigned to or can be assigned to a universally usable device for the automatic processing of data and for the sending and receiving of data respectively into the packet-switched network or out of the packet-switched network, and to which is assigned or can be assigned at least one data terminal device for the sending and receiving of data, in particular voice and/or packet data, respectively into the circuit-switched network or out of the circuit-switched network, is provided with a controllable switching facility which can be controlled in such a way that the data terminal device, which in a first operating mode is connected via the data transmission device to the circuit-switched network, can be switched over from the first operating mode to a second operating mode, in which the data terminal device is on one side connected via the data transmission device and the data processing device to the packet-switched network, and vice versa, that a change of operating mode occurs. 
   The present invention consists in the enhancement of a data transmission device which is, for example, constructed as a cordless base station, by the addition of a switchover capability, which is achieved in accordance with one embodiment preferably by software, so that the voice data streams can be forwarded to a data processing device, which in accordance with claim  24  preferably takes the form of a personal computer, notebook or server for the home and/or the office, and thus makes possible new applications. With a data transmission device devised in this way or with the cordless base station, as applicable, there is then a possibility of forwarding voice and/or signaling data streams to a data processing device, such as a personal computer, which is networked with the Internet. In this way, voice applications which are based on the Internet or a personal computer (such as, for example, Internet telephony, “voice messaging,” etc.) can be used by data terminal devices operated at the data transmission device. 
   As such, data terminal devices, (e.g., a cordless mobile module or a telephone), can switch a logical connection for voice data into the packet-switched network, (e.g., into the Internet or a local data network in the “home networking” scenario). 
   The main effect of this is to increase user-friendliness. The invention present enables applications, which at present are possible using a headset operated from a personal computer, also to be carried out also on a cordless mobile module. 
   The switchover capability in the cordless base station, in accordance with the present invention, allows the user the option of setting two operating modes on the cordless mobile module. 
   In a first operating mode, the cordless mobile module works like a normal telephone on the circuit-switched network. 
   In a second operating mode, the voice and protocol data are fed to the data processing device (e.g., a personal computer), or to the data network. In this case, there is no connection to the circuit-switched network. In addition, data about the user inputs to the cordless mobile module are forwarded to the personal computer, and display data is sent to the cordless mobile module by the personal computer. In addition, the voice channels are connected transparently to the personal computer, via a so-called tunnel connection. 
   This enables the cordless mobile module which is connected to the cordless base station to use an application which is running on the personal computer such as, for example, a headset. Additional applications can be activated by interactions with the user via display and control data, whereby the user friendliness, in particular, is further increased. In this way, for example, “Voice over Internet Protocol” telephony (VoIP telephony) becomes possible using a conventional cordless telephone (making the functionality of telephony available to all the applications in a network (e.g., a personal computer in a home network)). In addition, it is possible for the conventional cordless telephone to be used, for example, to perform online games, realize voice control functions in the home network, and operate devices in the home network remotely. 
   Using the present invention it is also possible, for example, to integrate conventional cordless telephones into a “connected home” scenario. In this situation, the personal computer serves as a “VoIP gateway” for “VoIP telephony.” Integration into games consoles, such as the X-Box, is also possible. 
   Further, the present invention offers the possibility of controlling applications on the data processing device via the data terminal device, on the basis of voice control and voice recognition mechanisms, of using the data terminal device as a remote control unit, of establishing access to Microsoft&#39;s Messenger Service via the data terminal device, of realizing an Internet radio, or Internet chatting using the cordless mobile module or a telephone, of converting text messages into voice messages (“Text to Speech”) so that, for example, e-mails can be read out, and/or of showing messages on the data terminal device&#39;s display. 
   However, the present invention may be used not only in the home situation as explained above, when the data transmission device takes the form of a cordless base station, the data terminal device a cordless mobile module and the data processing device a personal computer, but also may be used exactly the same in public fields if the data transmission device takes the form of a cellular mobile radio communication infrastructure, consisting of a base station and central switching equipment, the data terminal device takes the form of a mobile telephone, and the data processing device a server. 
   Additional features and advantages of the present invention are described in, and will be apparent from, the following Detailed Description of the Invention and the Figures. 

   
     BRIEF DESCRIPTION OF THE FIGURES 
       FIG. 1  shows a connection between a packet-switched and circuit-switched network as is known in the prior art. 
       FIG. 2  shows a first data sink/source for a circuit-switched and packet-switched network, consisting of a data terminal device, a data transmission device and a data processing device. 
       FIG. 3  based on  FIG. 2 , shows a second data sink/source for a circuit-switched and packet-switched network, consisting of a data terminal device and a data processing/data transmission device. 
       FIG. 4  shows an implementation of the first data sink/source using a cordless telephone and a personal computer. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 2  shows a first data sink/source DSQ 1  for a circuit-switched network LVN, preferably in the form of a “Public Switched Telephone Network (PSTN)” or an “Integrated Services Digital Network (ISDN),” and a packet-switched network PVN, preferably in the form of the Internet, consisting of a data terminal device DEE, a data transmission device DÜE and a data processing device DVG. 
   The data terminal device DEE contains a first central control unit ZSE 1 , a control facility STM and a first terminal device/transmission device interface EÜSS 1 . The first central control unit ZSE 1  is used to control the functional flows in the data terminal device DEE, and is connected both to the control facility STM and also to the first terminal device/transmission device interface EÜSS 1 . The data terminal device DEE is connected via the first terminal device/transmission device interface EÜSS 1  to the data transmission device DÜE, which has a second terminal device/transmission device interface EÜSS 2  for this connection. Either a first line link LV 1  or a first air link FRV 1  is provided as the link between the data terminal device DEE and the data transmission device DÜE. 
   Apart from the second terminal device/transmission device interface EÜSS 2 , the data transmission device DÜE also contains a second central control unit ZSE 2 , a first network/transmission device interface NÜSS 1 , a first switching facility USM 1  and a first device/transmission device interface GÜSS 1 . The second central control unit ZSE 2 , which is used to control the functional flows in the data transmission device DÜE and has a first switchover control facility USSM 1 , is connected to the second terminal device/transmission device interface EÜSS 2 , the first network/transmission device interface NÜSS 1 , and the first device/transmission device interface GÜSS 1 . Together with the first switching facility USM 1 , the first switchover control facility USSM 1  for the second central control unit ZSE 2  forms one functional unit such that the switchover control facility USSM 1  controls the switching facility USM 1 , which is represented in  FIG. 2  by the link between the two facilities. The data transmission device DÜE is connected, on the one hand, via the first network/transmission device interface NÜSS 1  to the circuit-switched network LVN and, on the other hand, via the first device/transmission device interface GÜSS 1  to the data processing device DVG, which for this connection has a second device/transmission device interface GÜSS 2 . For the link between the data transmission device DÜE and the data processing device DVG, either a second line link LV 2  is once again provided or a second air link FRV 2 . 
   In addition to the second device/transmission device interface GÜSS 2 , the data processing device DVG contains yet a third central control unit ZSE 3  and a first network/device interface NGSS 1 . The third central control unit ZSE 3 , which is used to control the functional flows in the data processing device DVG, and optionally has a second switchover control facility USSM 2 , shown dashed in  FIG. 2 , additional to the first switchover control facility USSM 1  of the second central control unit ZSE 2  in the data transmission device DÜE, is connected to the second device/transmission device interface GÜSS 2  and the first network/device interface NGSS 1 . The data processing device DVG is connected to the packet-switched network PVN via the first network/device interface NGSS 1 . 
   Below, using as a basis the explanation of the construction of the first data sink/source DSQ 1 , the way that the data sink/source DSQ 1  functions is explained in respect of the elimination of the logical separation between the first applications, which are based on the circuit-switched network LVN, and the second applications, based on the packet-switched network PVN. 
   From the point of view of the data terminal device DEE, which has until now, for example, been connected to the circuit-switched network LVN via the first line link LV 1  or the first air link FRV 1  and the data transmission device DÜE (cf., cordless base station as a data transmission device and cordless mobile telephone as a data terminal device in  FIG. 1 ), this means that the user of the data terminal device DEE can take advantage as desired of services on the circuit-switched network LVN, on the one hand, and of services on the packet-switched network PVN, on the other hand, in each case as the addressee and the sender. In other words, the transmission path from the data terminal device DEE to the circuit-switched network LVN and to the packet-switched network PVN must, in each case, be available to the user as required, that is it can be swapped by the user on demand (change of operating mode of the data terminal device). Thus, in a first operating mode, the data terminal device DEE is, for example, connected to the circuit-switched network LVN via the data transmission device DÜE, and in a second operating mode is connected to the packet-switched network PVN via the data transmission device DÜE and the data processing device DVG. 
   Because of the link, which already exists for the specified familiar scenario (data terminal device            circuit-switched network), between the data terminal device DEE and the data transmission device DÜE, the first switching facility USM 1  and the first switchover control facility USSM 1  are present in the data transmission device DÜE for this purpose, together possibly with the second switchover facility USSM 2  in the data processing device DVG and the control facility STM in the data terminal device DEE. Apart from the control facility STM in the data terminal device DEE, which preferably takes the form of a keyboard, all of the facilities mentioned preferably take the form of program modules (software). In place of the keyboard, however, it is also possible to use voice control.
   However, for each other conceivable scenario, the distribution of the facilities mentioned still could be different. This would be, for example, in the case of a scenario (data terminal device            packet-switched network) in which the data terminal device is, for example, connected to the packet-switched network via a line link or an air link and the data processing device. In this case, the switching facility and the switchover control facility preferably will be in the data processing device, while possibly there may be an additional switchover control facilities in the data transmission device.
   Alternatively, it is also possible to have configuration in which the data transmission device is connected to the packet-switched device and the data processing device to the circuit-switched network. 
   For the scenario on which  FIG. 2  is based (data terminal device           circuit-switched network), in which the first switching facility USM 1  is in the data transmission device DÜE, then depending on whether
   (i) only the first switchover control facility USSM 1  in the data transmission device DÜE, 
   (ii) the first switchover control facility USSM 1  in the data transmission device DÜE and also the second switchover control facility USSM 2  in the data processing device DVG, whereby both switchover control facilities USSM 1 , USSM 2 , control the first switching facility USM 1  in the data transmission device DÜE, 
   (iii) both the first switchover control facility USSM 1  in the data transmission device DÜE and also the second switchover control facility USSM 2  in the data processing device DVG, whereby however, unlike case (ii), only the first switchover control facility USSM 1  controls the first switching facility USM 1  in the data transmission device DÜE, 
   there are three embodiments of how the change of operating mode mentioned can be the achieved in the first data sink/source DSQ 1 . 
   Embodiment (i) 
   To describe this embodiment, it is now assumed that the data terminal device DEE is in the first operating mode, for example, in which the data terminal device DEE is linked to the circuit-switched network LVN via the data transmission device DÜE. Of course, the other case in which the data terminal device DEE is in the second operating mode, is also possible. 
   Suppose the user of the data terminal device DEE now wishes to swap into the second operating mode. The user of the data terminal device DEE initiates the operating mode change concerned by activating the control facility STM. Then, a first signal S 1 , to signal the change of operating mode, is transmitted from the data terminal device DEE via the first central control unit ZSE 1  and the first terminal device/transmission device interface EÜSS 1 , under the control of the former, via the first line link LV 1  or the first air link FRV 1 , as applicable, to the second terminal device/transmission device interface EÜSS 2  in the data transmission device DÜE, which forwards the first signal S 1  transmitted by the data terminal device DEE to the first switchover control facility USSM 1 . 
   The first switchover control facility USSM 1  then generates a second signal S 2  which it transmits to the data processing device DVG and, in turn, to the third central control unit ZSE 3 , by which the data processing device DVG is informed that the data terminal device DEE wishes to establish a connection to the packet-switched network PVN via the data processing device DVG. After the data processing device DVG has been informed, the first switchover control facility USSM 1  generates a third signal S 3  and transmits this to the first switching facility USM 1 . By the transmission of this third signal S 3 , the first switching facility USM 1  is instructed to close the transmission path to the circuit-switched network LVN, which the data terminal device DEE has until now, been using, and in its place to set up a new transmission path via the data processing device DVG to the packet-switched network PVN. In  FIG. 2 , this operation is indicated in the first switching facility USM 1  by the switch symbol. The data terminal device DEE is thereby connected to the packet-switched network PVN, via the second line link LV 2  or the second air link FRV 2 , as applicable, and the data processing device DVG. This transmission path, which belongs to the second operating mode, will now remain connected or set up, as applicable, until the user initiates a new operating mode change, in the same manner, this time a change from the second operating mode to the first operating mode. 
   In order to inform the user of the data terminal device about which operating mode the data terminal device is currently in, the operating mode which is active preferably should, in each case, be indicated on a display on the data terminal device (cf.  FIG. 4 ). It is possible in addition, for data terminal devices which are primarily used for voice transmission (telephony) (cf.  FIG. 4 ), and with which a “Voice over IP” connection is not yet possible, to give priority to the connection to the circuit-switched network rather than the packet-switched network. This can be achieved, for example, by a time-controlled default setting. As such, if a change of operating mode has been made as described from the first operating mode to the second operating mode and if, after a session in the second operating mode ends, the data terminal device has not been reset within a prescribed time, a resetting to the original state (default state) will be effected automatically. 
   Embodiment (ii) 
   To describe this embodiment, it is now again assumed that the data terminal device DEE is in the first operating mode, for example, in which the data terminal device DEE is linked to the circuit-switched network LVN via the data transmission device DÜE. Of course, the other case in which the data terminal device DEE is in the second operating mode, also is possible. 
   Suppose the user of the data terminal device DEE now wishes to swap into the second operating mode, or the first operating mode, as applicable. The user of the data terminal device DEE initiates the operating mode change concerned by activating the control facility STM. For each change, the same key or softkey can, for example, always be used, or different keys also may be used for the two operating mode changes. In the case of voice control, on the other hand, the matter is unambiguous, because the spoken operating mode change always will be effected. 
   At this point, a fourth signal S 4 , to signal the change of operating mode, is transmitted from the data terminal device DEE via the first central control unit ZSE 1  and the first terminal device/transmission device interface EÜSS 1 , under the control of the former, via the first line link LV 1  or the first air link FRV 1 , as applicable, to the second terminal device/transmission device interface EÜSS 2  in the data transmission device DÜE, via which the fourth signal S 4  transmitted from the data terminal device DEE is forwarded either to the first switchover control facility USSM 1  in the case of a change to the second operating mode (from which it follows that the current operating mode is the first operating mode), or in the case of a change to the first operating mode (from which it follows that the current operating mode is the second operating mode) via the first device/transmission device interface GÜSS 1 , the second line link LV 2  or the second air link FRV 2 , as applicable, and the second device/transmission device interface GÜSS 2 , in that order, to the second switchover control facility USSM 2  in the data processing device DVG. 
   On receiving the fourth signal S 4 , the first or second switchover control facility USSM 1 , USSM 2 , as applicable, will, in each case, then generate a fifth signal S 5 , with which the other switchover control facility concerned USSM 2 , USSM 1  is informed of the change in operating mode concerned. The fifth signal S 5  is transmitted via the first device/transmission device interface GÜSS 1 , the second line link LV 2  or the second air link FRV 2 , as applicable, and the second device/transmission device interface GÜSS 2 , or in the opposite direction, to the relevant switchover control facility USSM 2 , USSM 1 . After the relevant switchover control facility USSM 2 , USSM 1  has been informed of the change of operating mode, and with it the data processing device DVG or data transmission device DÜE, as applicable, the first or second switchover control facility USSM 1 , USSM 2 , as applicable, which received the fourth signal S 4  then generates a sixth signal S 6 , in each case, and transmits this to the first switching facility USM 1 . If the change is to the second operating mode, the first switchover control facility USSM 1  generates the sixth signal S 6 , while if the change is to the first operating mode, the second switchover control facility USSM 1  generates the sixth signal S 6 . By the transmission of this sixth signal S 6 , the first switching facility USM 1  is instructed to close the transmission path to the circuit-switched network LVN or to the packet-switched network, as applicable, which the data terminal device DEE has until now been using, and in its place to set up a new transmission path via the data processing device DVG to the packet-switched network PVN, or via the data transmission device DÜE to the circuit-switched network LVN, as appropriate. In  FIG. 2 , this operation is again indicated in the first switching facility USM 1  by the switch symbol. The data terminal device DEE is thereby connected, as applicable, either to the packet-switched network PVN, via the second line link LV 2  or the second air link FRV 2 , as applicable, and the data processing device DVG, or to the circuit-switched network LVN via the data transmission device DÜE. This transmission path, which belongs to the second operating mode or the first operating mode, as applicable, will now remain connected or set up, as applicable, until the user initiates another operating mode change in the same manner, this time a change from the second operating mode to the first operating mode, or from the first operating mode to the second operating mode, as applicable. 
   In order to inform the user about which operating mode the data terminal device is currently in, the operating mode which is active should again, in each case, preferably be indicated on a display on the data terminal device DEE (cf.,  FIG. 4 ). It is again possible, in addition, for data terminal devices which are primarily used for voice transmission (telephony) (cf.,  FIG. 4 ), and with which a “Voice over IP” connection is not yet possible, to give priority to the connection to the circuit-switched network rather than the packet-switched network. This can be achieved, for example, by a time-controlled default setting. As such, if a change of operating mode has been made as described, from the first operating mode to the second operating mode, or from the second operating mode to the first operating mode, as applicable, and if, after a session respectively in the second operating mode or first operating mode ends, the data terminal device has not been reset within a prescribed time, a resetting to the original state (default state) will be effected automatically. 
   Embodiment (iii) 
   To describe this embodiment, again it is now assumed that the data terminal device DEE is in the first operating mode, for example, in which the data terminal device DEE is linked to the circuit-switched network LVN via the data transmission device DÜE. Of course, the other case in which the data terminal device DEE is in the second operating mode, is again also possible. 
   Suppose the user of the data terminal device DEE now wishes to swap into the second operating mode, or the first operating mode, as applicable. The user of the data terminal device DEE initiates the operating mode change concerned by activating the control facility STM. For each change, the same key or softkey always can, for example, be used, or different keys also may be used for the two operating mode changes. In the case of voice control, on the other hand, the matter is unambiguous, because the spoken operating mode change will always be effected. 
   At this point, the fourth signal S 4 , to signal the change of operating mode, is again transmitted from the data terminal device DEE via the first central control unit ZSE 1  and the first terminal device/transmission device interface EÜSS 1 , again under the control of the former, via the first line link LV 1  or the first air link FRV 1 , as applicable, to the second terminal device/transmission device interface EÜSS 2  in the data transmission device DÜE, via which the fourth signal S 4  transmitted from the data terminal device DEE is forwarded either again to the first switchover control facility USSM 1  in the case of a change to the second operating mode (from which it follows that the current operating mode is the first operating mode), or again in the case of a change to the first operating mode (from which it follows that the current operating mode is the second operating mode) via the first device/transmission device interface GÜSS 1 , the second line link LV 2  or the second air link FRV 2 , as applicable, and the second device/transmission device interface GÜSS 2 , in that order, to the second switchover, control facility USSM 2  in the data processing device DVG. 
   On receiving the fourth signal S 4 , the first switchover control facility USSM 1  will then generate a seventh signal S 7 , with which it informs the second switchover control facility USSM 2  of the change in operating mode which has been signaled to it. The seventh signal S 7  is transmitted via the first device/transmission device interface GÜSS 1 , the second line link LV 2  or the second air link FRV 2 , as applicable, and the second device/transmission device interface GÜSS 2 , to the second switchover control facility USSM 2 . After the switchover control facility USSM 2  has been informed of the change of operating mode, and with it the data processing device DVG, the second switchover control facility USSM 2  which has received the seventh signal S 7  then generates an eighth signal S 8  and transmits this via the second device/transmission device interface GÜSS 2 , the second line link LV 2  or the second air link FRV 2 , as applicable, and the first device/transmission device interface GÜSS 1 , in that order, to the first switchover control facility USSM 1 . By this eighth signal S 8 , the second switchover control facility USSM 2  signals to the first switchover control facility USSM 1  that the latter should signal to the first switching facility USM 1 , and thus control, a change from the second operating mode to the first operating mode. The first switchover control facility USSM 1  then generates a ninth signal S 9 , and transmits this to the first switching facility USM 1 . By the transmission of the ninth signal S 9 , the first switching facility USM 1  is instructed to close the transmission path to the circuit-switched network LVN or to the packet-switched network PVN, as applicable, which the data terminal device DEE has, until now, been using, and in its place to set up a new transmission path via the data processing device DVG to the packet-switched network PVN, or via the data transmission device DÜE to the circuit-switched network LVN, as applicable. In  FIG. 2 , this operation is again indicated in the first switching facility USM 1  by the switch symbol. The data terminal device DEE is thereby connected as applicable either to the packet-switched network PVN, via the second line link LV 2  or the second air link FRV 2 , as applicable, and the data processing device DVG, or to the circuit-switched network LVN via the data transmission device DÜE. This transmission path, which belongs to the second operating mode or the first operating mode, as applicable, will now remain connected or set up, as applicable, until the user initiates another operating mode change, in the same manner, this time a change from the second operating mode to the first operating mode, or from the first operating mode to the second operating mode, as applicable. 
   In order to inform the user about which operating mode the data terminal device is currently in, the operating mode which is active should again, in each case, preferably be indicated on a display on the data terminal device DEE (cf.,  FIG. 4 ). It is again possible, in addition, for data terminal devices which are primarily used for voice transmission (telephony) (cf.,  FIG. 4 ), and with which a “Voice over IP” connection is not yet possible, to give priority to the connection to the circuit-switched network rather than the packet-switched network. This can be achieved, for example, by a time-controlled default setting. As such, if a change of operating mode has been made as described, from the first operating mode to the second operating mode, or from the second operating mode to the first operating mode, as applicable, and if, after a session respectively in the second operating mode or first operating mode ends, the data terminal device has not been reset within a prescribed time, a resetting to the original state (default state) will be effected automatically. 
   For the embodiments (i), (ii) and (iii) presented, it is an advantage if the operating mode change which is signaled using the signals S 2 , S 5 , S 7 , S 8  is acknowledged by whichever switchover control facility receives these signals, using a tenth signal S 10 , before the operating mode change is carried out by the first switching facility USM 1 . 
     FIG. 3  shows a second data sink/source DSQ 2  for a circuit-switched network LVN, preferably in the form of a “Public Switched Telephone Network (PSTN)” or an “Integrated Services Digital Network (ISDN),” and a packet-switched network PVN, preferably in the form of the Internet, including a data terminal device DEE and a data processing/data transmission device DVÜG. In the data processing/data transmission device DVÜG, the data processing device DVG shown in  FIG. 2  and the data transmission device DÜE shown in  FIG. 2  are combined to form a single constructional and functional unit. 
   The data terminal device DEE contains the first central control unit ZSE 1 , the control facility STM and the first terminal device/transmission device interface EÜSS 1 . The first central control unit ZSE 1  is used to control the functional flows in the data terminal device DEE, and is connected both to the control facility STM and to the first terminal device/transmission device interface EÜSS 1 . The data terminal device DEE is connected via the first terminal device/transmission device interface EÜSS 1  to the data processing/data transmission device DVÜG, which has a third terminal device/transmission device interface EÜSS 3  for this connection. Once again, either the first line link LV 1  or the first air link FRV 1  is provided as the link between the data terminal device DEE and the data processing/data transmission device DVÜG. 
   Apart from the third terminal device/transmission device interface EÜSS 3 , the data processing/data transmission device DVÜG also contains a fourth central control unit ZSE 4 , a second network/transmission device interface NÜSS 2 , a second switching facility USM 2  and a second network/device interface NGSS 2 . The fourth central control unit ZSE 4 , which is used to control the functional flows in the data processing/data transmission device DVÜG and has a third switchover control facility USSM 3 , is connected to the third terminal device/transmission device interface EÜSS 3 , the second network/transmission device interface NCSS 2 , and the second network/device interface NGSS 2 . 
   Together with the second switching facility USM 2 , the third switchover control facility USSM 3  for the fourth central control unit ZSE 4  forms one functional unit such that the switchover control facility USSM 3  controls the switching facility USM 1 , which is represented in  FIG. 3  by the link between the two facilities. The data processing/data transmission device DVÜG is connected, on the one hand, via the second network/transmission device interface NÜSS 2  to the circuit-switched network LVN, and, on the other hand, via the second network/device interface NGSS 2  to the packet-switched network PVN. 
   Below, using as a basis the explanation of the construction of the second data sink/source DSQ 2 , the way that the data sink/source DSQ 2  functions is explained in respect of the elimination of the logical separation between those first applications, which are based on the circuit-switched network LVN, and those second applications, which are based on the packet-switched network PVN. 
   For the scenario shown in  FIG. 3 , it is now assumed that the data terminal device DEE is in the first operating mode; for example in which the data terminal device DEE is linked to the circuit-switched network LVN via the data processing/data transmission device DVÜG. Of course, the other case in which the data terminal device DEE is in the second operating mode, is also possible. 
   Suppose the user of the data terminal device DEE now wishes to swap into the second operating mode. The user of the data terminal device DEE initiates the operating mode change concerned by activating the control facility STM. At this point, an eleventh signal S 11 , to signal the change of operating mode, is transmitted from the data terminal device DEE via the first central control unit ZSE 1  and the first terminal device/transmission device interface EÜSS 1 , under the control of the former, via the first line link LV 1  or the first air link FRV 1 , as applicable, to the third terminal device/transmission device interface EÜSS 3  in the data processing/data transmission device DVÜG, which forwards the eleventh signal S 11  transmitted by the data terminal device DEE to the third switchover control facility USSM 3 . 
   The third switchover control facility USSM 3  then generates a twelfth signal S 12  and transmits this to the second switching facility USM 2 . By the transmission of the twelfth signal S 12 , the second switching facility USM 2  is instructed to close the transmission path to the circuit-switched network LVN, which the data terminal device DEE until now has been using, and in its place to set up a new transmission path to the packet-switched network PVN. In  FIG. 3 , this operation is indicated in the second switching facility USM 2  by the switch symbol. The data terminal device DEE is thereby connected to the packet-switched network PVN. This transmission path, which belongs to the second operating mode, will now remain connected or set up, as applicable, until the user initiates another operating mode change, in the same manner, this time a change from the second operating mode to the first operating mode. 
   In order to inform the user of the data terminal device about which operating mode the data terminal device is currently in, the operating mode which is active preferably should, in each case, be indicated on a display on the data terminal device (cf.  FIG. 4 ). It is possible, in addition, for data terminal devices which are primarily used for voice transmission (telephony) (cf.,  FIG. 4 ), and with which a “Voice over IP” connection is not yet possible, to give priority to the connection to the circuit-switched network rather than the packet-switched network. This can be achieved, for example, by a time-controlled default setting. As such, if a change of operating mode has been made as described from the first operating mode to the second operating mode and if, after a session in the second operating mode ends, the data terminal device has not been reset within a prescribed time, a resetting to the original state (default state) will be effected automatically. 
     FIG. 4  shows the implementation of the first data sink/source DSQ 1  in  FIG. 2  in accordance with embodiment (i), using as the data terminal device and data transmission device a cordless telephone SLT, which is connected to the circuit-switched network LVN, together with a personal computer PC as the data processing device, this being connected to the packet-switched network. Apart from a screen (monitor) BSC, an input device EV consisting of a keyboard TA and a “mouse” MA, the personal computer PC has the devices as shown in  FIG. 2  in a system unit SYE. Thus, in addition to the third central control unit ZSE 3 , the system unit SYE also contains the second device/transmission device interface GÜSS 2 , which takes the form of a USB interface (Universal Serial Bus), and the first network/device interface NSSG 1  which takes the form of an Ethernet DSL interface (Digital Subscriber Line). The PC is connected to the cordless telephone SLT via a USB connection USBV, LV 2  as the second line link. As its data transmission device, the cordless telephone SLT has a cordless base station SLB, and as the data terminal device a cordless mobile module SLM, these being connected to each other via an radio link FRV 1  as the first air link. In addition to a display device (AE), the cordless mobile module SLM has an input unit EGE in the form of a keypad and an input facility EGM consisting of a microphone and an encapsulated speaker, the first central control unit ZSE 1  and, as the first terminal device/transmission device interface, a first radio interface EÜSS 1 . The display unit AE, the input unit EGE and the input facility EGM form the control facility STM shown in  FIG. 2 . In the cordless base station SLB are located the second central control unit ZSE 2  with the first switchover control facility USSM 1 , the first switching facility USM 1 , a second radio interface EÜSS 2  as a second terminal device/transmission device interface, a line connection NÜSS 1  as a first network/transmission device interface, and a further USB interface GÜSS 1  as a first device/transmission device interface. The connection to the circuit-switched network LVN is established via the line connection NCÜSS 1 , and the USB interface GÜSS 1  is connected to the USB interface GÜSS 2  in the personal computer PC via the USB link USBV, LV 2 . 
   If the cordless base station SLB is integrated into the personal computer PC as a cordless data adapter, then one obtains the second data sink/source DSQ 2  as shown in  FIG. 3 . 
   Although the present invention has been described with reference to specific embodiments, those of skill in the art will recognize that changes may be made thereto without departing from the spirit and scope of the present invention as set forth in the hereafter appended claims.