A method for switching from a first subscription of a first telecommunication network operator to a second subscription of a second telecommunication network operator on a plurality of smart cards, said method comprising, for each smart card: - Pre-provisioning said smart card with a batch of secret keys (Kis (#1 to #n)) at the level of a personalization factory; - Thanks to a first input file transmitted by said first telecommunication network operator to said personalization factory, generating at said personalization factory an output file 102) comprising a first secret key (Ki#1) selected in said batch, a corresponding first IMSI (IMSI#1) and a first ciphered operator code (OPc#1); - transmitting said output file to said first telecommunication network operator; - Transmitting OTA keys and said first IMSI (IMSI#1) to an OTA server of a service provider managing said smart card in order to attach said smart card to said first telecommunication network; - If said service provider wants to switch from said first subscription to said second subscription without changing said smart card: ∘ Thanks to a second input file transmitted by said second telecommunication network operator to said personalization factory, transmitting to said second telecommunication network operator an output file comprising a second secret key (Ki#2) selected in said batch of secret keys, a second ciphered operator code (OPc#2) and a second IMSI (IMSI#2); ∘ Transmitting said second IMSI (IMSI#2), said second ciphered operator code (OPc#2) and a second couple of constants (Ri#2, Ci#2) to said service provider; ∘ Downloading over-the-air by said service provider to said smart card said ciphered operator code (OPc#2), said second couple of constants (Ri#2, Ci#2), said second IMSI (IMSI#2), in order to associate said second secret key (Ki#2) with said second ciphered operator code (OPc#2) and said second IMSI (IMSI#2), and order said smart card to switch to said second secret key (Ki#2), to said second IMSI (IMSI#2) and to said second ciphered operator code (OPc#2) before making a Refresh, in order to attach said smart card to the network of said second telecommunication network operator. - Pre-provisioning said smart card with a batch of secret keys (Kis (#1 to #n)) at the level of a personalization factory; - Thanks to a first input file transmitted by said first telecommunication network operator to said personalization factory, generating at said personalization factory an output file 102) comprising a first secret key (Ki#1) selected in said batch, a corresponding first IMSI (IMSI#1) and a first ciphered operator code (OPc#1); - transmitting said output file to said first telecommunication network operator; - Transmitting OTA keys and said first IMSI (IMSI#1) to an OTA server of a service provider managing said smart card in order to attach said smart card to said first telecommunication network; - If said service provider wants to switch from said first subscription to said second subscription without changing said smart card: ∘ Thanks to a second input file transmitted by said second telecommunication network operator to said personalization factory, transmitting to said second telecommunication network operator an output file comprising a second secret key (Ki#2) selected in said batch of secret keys, a second ciphered operator code (OPc#2) and a second IMSI (IMSI#2); ∘ Transmitting said second IMSI (IMSI#2), said second ciphered operator code (OPc#2) and a second couple of constants (Ri#2, Ci#2) to said service provider; ∘ Downloading over-the-air by said service provider to said smart card said ciphered operator code (OPc#2), said second couple of constants (Ri#2, Ci#2), said second IMSI (IMSI#2), in order to associate said second secret key (Ki#2) with said second ciphered operator code (OPc#2) and said second IMSI (IMSI#2), and order said smart card to switch to said second secret key (Ki#2), to said second IMSI (IMSI#2) and to said second ciphered operator code (OPc#2) before making a Refresh, in order to attach said smart card to the network of said second telecommunication network operator. ∘ Thanks to a second input file transmitted by said second telecommunication network operator to said personalization factory, transmitting to said second telecommunication network operator an output file comprising a second secret key (Ki#2) selected in said batch of secret keys, a second ciphered operator code (OPc#2) and a second IMSI (IMSI#2); ∘ Transmitting said second IMSI (IMSI#2), said second ciphered operator code (OPc#2) and a second couple of constants (Ri#2, Ci#2) to said service provider; ∘ Downloading over-the-air by said service provider to said smart card said ciphered operator code (OPc#2), said second couple of constants (Ri#2, Ci#2), said second IMSI (IMSI#2), in order to associate said second secret key (Ki#2) with said second ciphered operator code (OPc#2) and said second IMSI (IMSI#2), and order said smart card to switch to said second secret key (Ki#2), to said second IMSI (IMSI#2) and to said second ciphered operator code (OPc#2) before making a Refresh, in order to attach said smart card to the network of said second telecommunication network operator.