A transmission network is, for example, a telephone network for transmitting analog or digital voice data in voice channels, such as a public telephone network. However, transmission networks in which the data to be transmitted is transmitted in data packets are also known. An example of such a transmission network is the Internet, in which voice data is transmitted in data packets according to a protocol which is also referred to as Voice over Internet Protocol, abbreviated to VoIP.
Copper double conductors of the telephone network are used, for example, as the connection route for the first terminal and the second terminal. For the broadband transmission of data on copper double conductors there are various technologies, which are combined under the term xDSL technologies (X Digital Subscriber Line). For example there are HDSL (High Bit Rate Digital Subscriber Line), ADSL (Asymmetrical Digital Subscriber Line) and VDSL (Very High Bit Rate Digital Subscriber Line). Specifically for Internet applications, the Universal ADSL standard has been defined, abbreviated to UADSL or UDSL. With this technology, a personal computer can be installed directly on the copper double conductor without the use of what is referred to as a splitter. The transmission speeds are 1.5 megabit/second.
The document WO 99/14924 discloses a system in which a subscriber utilizes a transmission route to a switching office, either for transmitting data to an Internet or for transmitting data to a public telephone network. During the connection to the Internet, the subscriber cannot be reached via the public telephone network because the transmission route between the switching office and his subscriber connection is seized by the Internet connection. Using the system described in the document WO 99/14924 it is possible to inform the called subscriber about a call, directed to him in the public telephone network, of a calling subscriber by transmitting data in addition to the Internet data. The called subscriber then has the possibility of setting up a connection to the calling subscriber.
The document EP 0 926 867 A2 discloses a possibility of informing a called subscriber of a call of a calling subscriber in a public telephone network if the called subscriber is using the single transmission route to transmit data to an Internet. Further data which contains information relating to the call of the calling subscriber is transmitted to the called subscriber by a switching office to which there is an Internet connection. The called subscriber then has the possibility of accepting or rejecting the call of the calling subscriber.
The document XP-000720563, “Convergence between public switching and the Internet”, Dr. U. Schoen, J. Hamann, A. Jugel, Dr. H. Kurzawa, C. Schmidt; Siemens AG—Germany, discloses how broadband transmission routes are used to transmit data to a subscriber. These broadband transmission routes make it possible to transmit large amounts of data between a switching device and the subscriber terminals. In particular this is advantageous for transmitting in a reasonable amount of time the large amounts of data which are usually to be transmitted in the case of Internet connections. This document indicates possibilities of how existing elements of a public telephone network can be upgraded in order to achieve better data transmission of Internet data.