A method of replacing at least one authentication parameter (K1, K2, K3) for authenticating a security element co-operating with a terminal, said authentication parameter (K1, K2, K3) enabling an authentication system of a mobile network to authenticate said security element, said mobile network being operated by a mobile network operator, said method consisting in: A - Having an entity store in said security element a first authentication parameter (K1, K2, K3); B - Having said entity transmit to said mobile network operator said first authentication parameter (K1, K2, K3) so that said operator can record it in its authentication system for authenticating said security element; C - On occurrence of an event, having a remote platform transmit to said security element an indicator informing said security element that it is authorized to replace said first authentication parameter (K1, K2, K3) with a second authentication parameter (K1, K2, K3) if the authentication of said security element fails with said authentication system the next time it attempts to connect to said mobile network; D - On occurrence of said event, having said entity transmit to said operator a second authentication parameter (K1, K2, K3) so as to enable said operator to replace said first authentication parameter (K1, K2, K3) by said second authentication parameter (K1, K2, K3) in its authentication system; E - In the event of subsequent failure of said security element to connect to said mobile network with said first authentication parameter (K1) and if said indicator is present at said security element, replacing said first authentication parameter (K1, K2, K3) with said second authentication parameter (K1, K2, K3) at said security element so that said security element can authenticate itself with said mobile network by means of said second authentication parameter (K1, K2, K3). A - Having an entity store in said security element a first authentication parameter (K1, K2, K3); B - Having said entity transmit to said mobile network operator said first authentication parameter (K1, K2, K3) so that said operator can record it in its authentication system for authenticating said security element; C - On occurrence of an event, having a remote platform transmit to said security element an indicator informing said security element that it is authorized to replace said first authentication parameter (K1, K2, K3) with a second authentication parameter (K1, K2, K3) if the authentication of said security element fails with said authentication system the next time it attempts to connect to said mobile network; D - On occurrence of said event, having said entity transmit to said operator a second authentication parameter (K1, K2, K3) so as to enable said operator to replace said first authentication parameter (K1, K2, K3) by said second authentication parameter (K1, K2, K3) in its authentication system; E - In the event of subsequent failure of said security element to connect to said mobile network with said first authentication parameter (K1) and if said indicator is present at said security element, replacing said first authentication parameter (K1, K2, K3) with said second authentication parameter (K1, K2, K3) at said security element so that said security element can authenticate itself with said mobile network by means of said second authentication parameter (K1, K2, K3). <EOS>