Abstract: Method and processor (12) for: a. setting up a telecommunication link between various communication appliances (1, 2, 3, 7, 8, 9); b. setting up a monitoring link (13) between the telecommunication link and the processor (12); c. the storage in enciphered form of a first identity of either a first user of a first communication appliance (1, 2, 3) or of the first communication appliance (1, 2, 3) and a second identity of either a second user of a second communication appliance (7, 8, 9) or of the second communication appliance (7, 8, 9); d. the storage of the data despatched via the telecommunication link, which data have been enciphered prior to the storage using a symmetrical conversation key; e. the storage of the conversation key enciphered using public keys of the users; f. the signing of the data stored using the symmetrical conversation key and also of the first and second identities stored in enciphered form.

Abstract: Telecommunication system in which local terminals may be called from one or more central stations by way of transmission paths selected by selection device on the probability of success. Selection takes place with the help of selection tables on the basis of exchanged signalling messages obtained from, or by way of, a switching system (3); other selection tables are also possible, e.g., on the basis of geographic or cartographic information. To the transmission paths there are assigned scores on the basis of the points in time of successful and unsuccessful calls, and of numbers of successful calls. During a session, a call is first made by way of the transmission path having the highest score (S(ok), S(nok) or S(rc)) in one of the selection tables (OK, NOK and RC, respectively). In the event of failure, the call is repeated by way of a preferred transmission path (PP), once again in sequence of the scores from one of the selection tables.