Abstract: The invention specifies a method and an arrangement for testing and maintaining a switching center in a telecommunications network and the lines and appliances connected thereto, where control is effected using a test unit provided for this purpose which is connected to any digital subscriber line. This results in a significant increase in the scope of use for the test system, simple introduction of new test methods, performance of extensive tests with a single test unit, and fast and secure data transmission.

Abstract: The present invention relates to a system and method in which user data is initially transmitted to a first network gateway by means of a first data transmission network. The user data is encoded according to a first encoding type. The network gateway feeds the user data into a circuit-switching network without further code conversion. The original encoding type and a second encoding type, permissible in the circuit-switching network, are signaled to the circuit-switching network. The signaling of the first encoding type is transferred by the circuit-switching network to a further network gateway unprocessed. The user data is transmitted in the data transmission network as if encoded by means of the permissible encoding type.

Abstract: A process in which a signaling unit contains at least two line units which are used when setting up a connection for the transmission of user data in data packets wherein the line units in each case terminate the signaling with respect to one of the terminal devices involved in the data transmission and exchange internal signaling messages with one another to allow the signaling to be carried out in a simple manner.