1. A method of controlling data transmission between a subscriber-end transceiver and an exchange-end transceiver connected to each other by a data transmission path, the method comprising:
generating a deactivation signal at a system control device when a data stream to be transmitted carries no payload in either of two data stream directions;
in response to the deactivation signal, storing exchange-end transmission coefficients for the data transmission path in an exchange memory of an exchange-end transceiver;
transmitting the deactivation signal on the data transmission path from the exchange-end transceiver to the subscriber-end transceiver;
in response to receiving the deactivation signal, storing subscriber-end transmission coefficients for the data transmission path in a subscriber-end memory unit in the subscriber-end transceiver;
transmitting the deactivation signal back to the exchange-end transceiver from the subscriber-end transceiver on the data transmission path;
in response to receiving the deactivation signal back from the subscriber-end transceiver, stopping data transmission on the data transmission path at the exchange-end transceiver;
in response to detecting the stopping of data transmission at the exchange-end transceiver, stopping data transmission at the subscriber-end transceiver;
placing the exchange-end transceiver and the subscriber-end transceiver in a stand-by state; wherein the exchange-end transceiver and the subscriber-end transceiver are configured to use first and second operational channels to preset parameters for a stand-by state, and to use first and second operational channels to preset parameters for a hot start; and
continuously interrupting the stand-by state with a device selected from the group consisting of the exchange-end transceiver and the subscriber-end transceiver to inspect a characteristic of the data transmission path by requesting a signal indicative of the characteristics of the data transmission path; and
on the basis of the requested signal, matching an echo elimination device and an equalization device to the characteristics of the data transmission path.', 'generating a deactivation signal at a system control device when a data stream to be transmitted carries no payload in either of two data stream directions;', 'in response to the deactivation signal, storing exchange-end transmission coefficients for the data transmission path in an exchange memory of an exchange-end transceiver;', 'transmitting the deactivation signal on the data transmission path from the exchange-end transceiver to the subscriber-end transceiver;', 'in response to receiving the deactivation signal, storing subscriber-end transmission coefficients for the data transmission path in a subscriber-end memory unit in the subscriber-end transceiver;', 'transmitting the deactivation signal back to the exchange-end transceiver from the subscriber-end transceiver on the data transmission path;', 'in response to receiving the deactivation signal back from the subscriber-end transceiver, stopping data transmission on the data transmission path at the exchange-end transceiver;', 'in response to detecting the stopping of data transmission at the exchange-end transceiver, stopping data transmission at the subscriber-end transceiver;', 'placing the exchange-end transceiver and the subscriber-end transceiver in a stand-by state; wherein the exchange-end transceiver and the subscriber-end transceiver are configured to use first and second operational channels to preset parameters for a stand-by state, and to use first and second operational channels to preset parameters for a hot start; and', 'continuously interrupting the stand-by state with a device selected from the group consisting of the exchange-end transceiver and the subscriber-end transceiver to inspect a characteristic of the data transmission path by requesting a signal indicative of the characteristics of the data transmission path; and', 'on the basis of the requested signal, matching an echo elimination device and an equalization device to the characteristics of the data transmission path.

2. The method of claim 1, further comprising configuring the exchange-end transceiver to selectively cancel the deactivation signal during data transmission to prevent deactivation of the exchange-end transceiver and the subscriber-end transceiver.

3. The method of claim 1, further comprising configuring the subscriber-end transceiver to selectively cancel the deactivation signal during data transmission to prevent deactivation of the exchange-end transceiver and the subscriber-end transceiver.

4. The method of claim 1, further comprising generating a sub scriber-end transmission stop in response to detecting a first synchronization error signal.

5. The method of claim 1, further comprising generating a subscriber-end transmission stop in response to detecting a failure of a signal level on the data transmission path.

6. The method of claim 1, further comprising entering an exchange-end stand-by state in response to a second synchronization error signal.

7. The method of claim 1, further comprising entering an exchange-end stand-by state in response to an exchange-end transmission stop.

8. A data-transmission system comprising:
an exchange-end transceiver;
a subscriber-end transceiver;
a data transmission path for communicating a data stream between the exchange-end transceiver and the subscriber-end transceiver;
an exchange-end coefficient memory for storage of exchange-end transmission coefficients associated with the data transmission path;
a subscriber-end coefficient memory for storage of subscriber-end transmission coefficients associated with the data transmission path; and
a system controller configured to provide the exchange-end memory unit with a deactivation signal when the data stream contains no payload; wherein the exchange-end coefficient memory and the subscriber-end coefficient memory are configured to use first and second operational channels to preset parameters for a stand-by state, and to use first and second operational channels to preset parameters for a hot start; and
a device selected from the group consisting of the exchange-end transceiver and the subscriber-end transceiver configured to continuously interrupt the stand-by state to inspect a characteristic of the data transmission path by requesting a signal indicative of the characteristics of the data transmission path; and
on the basis of the requested signal, the device being configured to match an echo elimination device and an equalization device to the characteristics of the data transmission path.', 'an exchange-end transceiver;', 'a subscriber-end transceiver;', 'a data transmission path for communicating a data stream between the exchange-end transceiver and the subscriber-end transceiver;', 'an exchange-end coefficient memory for storage of exchange-end transmission coefficients associated with the data transmission path;', 'a subscriber-end coefficient memory for storage of subscriber-end transmission coefficients associated with the data transmission path; and', 'a system controller configured to provide the exchange-end memory unit with a deactivation signal when the data stream contains no payload; wherein the exchange-end coefficient memory and the subscriber-end coefficient memory are configured to use first and second operational channels to preset parameters for a stand-by state, and to use first and second operational channels to preset parameters for a hot start; and', 'a device selected from the group consisting of the exchange-end transceiver and the subscriber-end transceiver configured to continuously interrupt the stand-by state to inspect a characteristic of the data transmission path by requesting a signal indicative of the characteristics of the data transmission path; and', 'on the basis of the requested signal, the device being configured to match an echo elimination device and an equalization device to the characteristics of the data transmission path.

9. The data-transmission system of claim 8, wherein the exchange-end transceiver is configured to selectively cancel the deactivation signal during data transmission to prevent deactivation of the exchange-end transceiver and the subscriber-end transceiver.', '10. The data-transmission system of claim 8, wherein the subscriber-end transceiver is configured to selectively cancel the deactivation signal during data transmission to prevent deactivation of the exchange-end transceiver and the subscriber-end transceiver.']