Abstract: In the course of the intercommunication between the base station and the autonomous telephone set, the first means of authentication initially generates a keyword dependent on the call charge for the current service and transmits it to the autonomous telephone set. The second means of authentication then calculates the transform of the keyword by the encryption function F with the aid of the subscriber's secret key, and transmits the transform to the first means of authentication which finally checks the authenticity of the transform to totally block the intercommunication if the authenticity is not confirmed by the check.

Abstract: In a telephone installation, telephone rental data is loaded remotely into an independent station in the following manner.In response to a request for a call coming from the independent station and in the presence of a load request signal, a control means searches all the telephone rental data relative to the independent station as well as that indicating an order for the remote loading. A coding means codes with the help of a special key data which is secret. A processing means authorises the transmission of non-secret pubic telephone rental data as well as secret data thus encoded to the said independant station according to the order for the remote loading.At the independent station a decoding means deciphers the coded secret telephone rental data thus received with the help of the special key and a processing means stores the non-secret public telephone rental data thus transmitted and secret data thus decoded in a memory of the independent station.

Abstract: The power transmitted by an r.f. transmitting and receiving station, such as a mobile station, to a fixed base station, is controlled as a function of power received by the mobile station to obtain a constant receiving power level in the fixed station despite variations in the relative location of the stations. The power received by the mobile station is measured and sampled at predetermined instants. At each predetermined instant, the power to be received by the mobile station at a following predetermined instant is estimated as a function of the measured power, to derive an estimated power. R.f. signal power transmitted by the mobile station is reduced between the successive instants in proportion to the estimated power.