Method for establishing a secure communication between a user terminal comprising a SIM application and a push manager server, when said SIM application detects that there is no signature key configured, said method triggers the following steps: - generating by said SIM application a random client number (Rc), - sending, to the push manager server, said random client number (Rc), an application proprietary protocol related fields and a session id, - generating by said push manager server a random server number (Rs), - generating by said push manager server a first signature key, the first signature key being derived from the random client number (Rc), the random server number (Rs) and a shared string known by the push server and the SIM application using a cryptographic method, - sending, to said SIM application, said random server number (Rs), said first signature key and said session id, - checking said session id by said SIM application, - generating by said SIM application a second signature key if said session id received from the push manager server is similar to said session id sent by said SIM application, the second signature key being derived from the random client number (Rc), the random server number (Rs) and the shared string using the same cryptographic method as the one used to generate the first signature key; - decreasing by said SIM application a provision counter by 1, - generating by said SIM application a status code, said status code indicating if the second signature key is successfully generated or unsuccessfully generated, the second signature key being considered as successfully generated if it is identical to the first signature key; - generating by said SIM application a signed acknowledgment, said signed acknowledgment being generated by using the second signature key to encrypt the status code, - sending, to the push message server, said signed acknowledgment and said session id, - decrypting said encrypted status code by using the first signature key, if said status code is: ∘ successful, then the secure communication is established, ∘ unsuccessful, then the secure communication is not established. - generating by said SIM application a random client number (Rc), - sending, to the push manager server, said random client number (Rc), an application proprietary protocol related fields and a session id, - generating by said push manager server a random server number (Rs), - generating by said push manager server a first signature key, the first signature key being derived from the random client number (Rc), the random server number (Rs) and a shared string known by the push server and the SIM application using a cryptographic method, - sending, to said SIM application, said random server number (Rs), said first signature key and said session id, - checking said session id by said SIM application, - generating by said SIM application a second signature key if said session id received from the push manager server is similar to said session id sent by said SIM application, the second signature key being derived from the random client number (Rc), the random server number (Rs) and the shared string using the same cryptographic method as the one used to generate the first signature key; - decreasing by said SIM application a provision counter by 1, - generating by said SIM application a status code, said status code indicating if the second signature key is successfully generated or unsuccessfully generated, the second signature key being considered as successfully generated if it is identical to the first signature key; - generating by said SIM application a signed acknowledgment, said signed acknowledgment being generated by using the second signature key to encrypt the status code, - sending, to the push message server, said signed acknowledgment and said session id, - decrypting said encrypted status code by using the first signature key, if said status code is: ∘ successful, then the secure communication is established, ∘ unsuccessful, then the secure communication is not established. ∘ successful, then the secure communication is established, ∘ unsuccessful, then the secure communication is not established.