Method for transmitting data of a mobile radio network, in particular GSM data, between a calling subscriber, to which a first code conversion device is assigned, and a called subscriber, to which a second code conversion device is assigned, whereby a predefined frame format is used for the transmission, with the following measures: - the data stream between the code conversion devices (TCE1, TCE2) is divided into a first data stream having speech sampling values, particularly PCM speech sampling values, for transmission and into a second data stream having signal parameters for speech data reconstruction, particularly TRAU frames; - the data streams divided in this manner are transmitted simultaneously by the first code conversion device via an A interface, via which the first code conversion device is connected to a switching device, during a TFO, tandem-free operation, mode; - in the event of a handover from the second code conversion device to a non-TFO code conversion device, termination of the signal parameters arriving from the second code conversion device is registered in the first code conversion device, and a first predetermined time, T release, starts, whereby after the first predetermined time, T release, has elapsed, data arriving from the A interface are encoded, whereby speech sampling values "PCM*" decoded for the TRAU frames are inserted into the data stream departing for the A interface, whereby the TRAU sent first is a TRAU*, whereby the speech sampling values "PCM*" are the speech sampling values with the processed high-order 6 bits, whereby the TRAU* is a piece of identification information; and - whereby a second predetermined time, T sync, starts in the first code conversion device, whereby the first code conversion device reverts to a normal mode, in which the speech sampling values are coded and decoded, after the second predetermined time, T sync, has elapsed. - the data stream between the code conversion devices (TCE1, TCE2) is divided into a first data stream having speech sampling values, particularly PCM speech sampling values, for transmission and into a second data stream having signal parameters for speech data reconstruction, particularly TRAU frames; - the data streams divided in this manner are transmitted simultaneously by the first code conversion device via an A interface, via which the first code conversion device is connected to a switching device, during a TFO, tandem-free operation, mode; - in the event of a handover from the second code conversion device to a non-TFO code conversion device, termination of the signal parameters arriving from the second code conversion device is registered in the first code conversion device, and a first predetermined time, T release, starts, whereby after the first predetermined time, T release, has elapsed, data arriving from the A interface are encoded, whereby speech sampling values "PCM*" decoded for the TRAU frames are inserted into the data stream departing for the A interface, whereby the TRAU sent first is a TRAU*, whereby the speech sampling values "PCM*" are the speech sampling values with the processed high-order 6 bits, whereby the TRAU* is a piece of identification information; and - whereby a second predetermined time, T sync, starts in the first code conversion device, whereby the first code conversion device reverts to a normal mode, in which the speech sampling values are coded and decoded, after the second predetermined time, T sync, has elapsed.