machine 12 therefore encrypts using the old key this provides the possibility of annulling or correcting the last transaction and thus avoiding harm to the user or to the data center 18 the flowchart according to fig3 a and 3b shows the method for changing value and reloading in that case wherein the communication between the postage meter machine 12 and the data center 18 ensues automatically via modem since the steps of the method are essentially the same as in the method according to fig2 a and 2b the individual steps are provided with the same reference numerals incremented by twenty as in the method set forth with reference to fig2 a and 2b the user of the postage meter machine 12 after turning the machine 12 on enters the postage telephone number or identity number pin and confirms this entry by actuating the special key 52 the stored selected value is now displayed the user either confirms this value by actuation of the special key 52 or overwrites it with a new selected value that is likewise confirmed by the actuation of the special key 52 all further steps now sequence automatically without further input from the user of the postage meter machine 12 between the postage meter machine 12 and the data center 18 in the same way as was set forth in the voice method described with reference to fig2 a and 2b the sole difference is that only the cryptomessages i e the encrypted messages and not the abbreviated code numbers acquired therefrom are exchanged between the postage meter machine 12 and the data center 18 in the modem method a method for storing security related data particularly during the remote value setting.