Abstract: In a GSM type system, home location register resets after some incidents are programmed from a back-up register. The invention proposes that mobile service switching centers create a difference between two classes of update requests which they send to the home location register in two different situations. In the first class a message following a change of area by a mobile station takes priority. In the second class a message follows a home location register reset and tends to (frequently unnecessarily) re-establish the conformity of the data in the home location register and in the visitor location registers of the centers. The second class is assigned a low priority level which prevents problems with the availability of the home location register. Application to telephony.

Abstract: A data processing machine comprises a plurality of elementary machines (SUPMS, DEP, ARR, . . . ) disposed in a plurality of levels (level 1, level 2, . . .), and an event presentation device (PTA) responding to the arrival of an event by identifying the lowest machine level that is active and by identifying the elementary machine that is active in this lowest active machine level to present the event to said active elementary machine.