The D network is digitized, both in terms of dial-up switching (signaling) and for the transmission of data and voice. The latter are quantized, digitized and pulse- code modulated, making them low- interference and regenerable and thus capable of being transmitted even under difficult conditions. A special feature of this cellular network is automatic handover and automatic location of subscribers whose location is not known, even if there is currently no call in progress and no data connection, i.e. roaming.
Transmission takes place in the 900 MHz range, in the subranges 890 MHz to 915 MHz and 935 MHz to 960 MHz. The lower frequency range is used for transmission from the mobile radio transmitter/ receiver to the base station( uplink), the upper one for the opposite direction( downlink). The mobile station is referred to as a cell phone and has a transmitting power of 0.8 W to 5 W. The frequency ranges, each 25 MHz wide, are divided into 124 channels, each of which is 200 kHz wide.
There are two operators for the D-network: T-Mobil with its D1 network and Vodafone with its D2 network. Since both networks are operated according to the GSM standard, there are hardly any technical differences. The network codes are different so that the two operators can be distinguished by their phone numbers.