GF82.70-P-0005R General Information on Telephone (Cellular Radio Network) Function

GF82.70-P-0005R General Information On Telephone (cellular Radio Network) Function
- with CODE (386) Preinstallation for telephone "Handy", UPCI system
- with CODE (387) Preinstallation for telephone "Handy", UPCI system, USA/Canada
- with CODE (388) Telephone "Handy", UPCI system

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General information on cellular radio network
The cellular radio network is a digital, cellular radio network as under the GSM standard Global System Mobile). GSM standard (stands for the normalization of a radio telephone system. The objective is to provide a compatible digital cellular radio service worldwide. To this end the switching center, language and data are transmitted digitally. Apart from this additional services are offered such as, e.g.:
^ fee display
^ conference calls, waiting function
^ identification of calling party
^ call relaying
^ Fax
^ access to text and terminals (ISDN compatible)

Radio transmission in the cellular radio network is performed - depending on the provider or country - in the 900 - 1900 MHz range between the portable CTEL and base transceiver station (BTS).

As from the base transceiver station all signals are forwarded cable-specific to the base transceiver station (BSC). In a cellular radio network the base transceiver stations are arranged such that the honeycombed radio cells form a network to supply the mobile subscribers. Radio cells have to cover high subscriber densities in densely populated areas, and in contrast cover larger transmission areas in rural areas. Depending on requirements these radio cells can extend from 100 m and 40 km.

A characteristic of cellular radio network is the automatic handover procedure from one radio cell to the next, without this being perceived by the mobile subscribe If during a communication the transmission range of a base transceiver station is left and a change is made to the transmission range of the next base transceiver station, communication can be maintained without any interruption, although the transmitter of the next base transceiver station is operating on another frequency.

This handover procedure is performed within 5 ms to 10 ms. Transmission problems may occur if the user is located in valley or low spots (radio shadows) or in areas with a minimum number of transceiver stations. This can, however, be eliminated by moving to another location.

It is possible, to make calls abroad using one's own cellular phone and a SIM card (Subscriber Identity Module).

This is contingent on each country also having the GSM standard, a corresponding contract (roaming contract) between the country and the network provider and the cellular phone is compatible with the various frequencies, i.e. a dualband or triband device. A radio cell is formed by the base transceiver station and this is the actual transceiver station. The base transceiver station sets up communication to the cellular phone, checks the radio transmission and forwards the information cable-specific to the base transceiver station.
In the GSM standard each base transceiver station has - depending on the frequency - 124 or 372 channels available to it. The base transceiver controller is the base transceiver station's control unit. Base transceiver control is between the base transceiver stations and the mobile service switching centers (MSC). Here useful data for voice and data communication, as well as for monitoring and control functions are transmitted. In addition to this the base transceiver station is the central control point for automatic handover from one radio cell to the next one.

The mobile service switching centers are networked and form the switching system in the mobile radio networks with GSM standard. Here, user and visitor data are stored in various databases and registers.

Databases and registers in mobile service switching centers (MSC)
^ Home location register (HLR)
Here the subscriber master data such as name, address, telephone number, service features, caller and calling party identification numbers, details on time, duration and charges for call, as well as details on the radio cells in which a connection is established and terminated are stored.

^ Equipment identification register (EIR)
Here the equipment-specific, electronic identification number (IMEI number) of the cellular phone is registered. When logging-in, this number is transmitted by the cellular phone. If the phone in question has been locked/stolen, then network authorization is rejected.

^ Visitor location register (VLR)
The necessary data of a visiting subscriber are temporarily stored here.

^ Authentication center (AC)
The mobile subscriber is authenticated here in terms of access authorization and the corresponding connection is established.

The public telephone network is designated in its entirety as a public switched, telephone network (PSTN).