Method to upgrade a Trusted Application (TA) in an Execution Environment (TEE) compliant to a Trusted Execution Environment standard to an as-a-server functioning, said standard defining at least one of the following locks preventing the Trusted Application (TA) in a Trusted Execution Environment (TEE) to function as-a-server: a Customer Application (CA) having a session opened in an instance of a Trusted Application (TA) enters in a blocking state immediately after having sent a Command (Ci) to the Trusted Application (TA) and while the Trusted Application's Task has not finished, a Trusted Application (TA) cannot partially execute a Task, an execution context of a Trusted Application (TA) is deleted between an executed Task and a subsequent command in an opened instance/session, a Trusted Application (TA) has to be Single Instance/Multi Session or Multi Instance/Single Session, said method running, inside the Trusted Execution Environment (TEE), each instance of a Multi Instance/Single Session Trusted-Server Trusted Application (TS) compliant to the TEE standard in an infinite state-full loop polling (SPi) a session of a Single Instance/Multi Session Trusted-Pipe Trusted Application (TP), the single session of each of the instances of the Trusted-Server Trusted Application (TS) being adapted to perform a task as a server, while said Trusted-Pipe Trusted Application (TP) being further polled (GPi) by the Customer Application (CA) and opening session depending on command coming from the Customer Application (CA), this polling mechanism making said Trusted-Pipe Trusted Application (TP) functioning as a mailbox for said Customer Application (CA) and said Trusted-Server Trusted Application (TS) to exchange data asynchronously, while accomplishing their respective tasks without blocking each other and enabling the Trusted-Server Trusted Application (TS) to request data within its currently executing task without stopping it. a Customer Application (CA) having a session opened in an instance of a Trusted Application (TA) enters in a blocking state immediately after having sent a Command (Ci) to the Trusted Application (TA) and while the Trusted Application's Task has not finished, a Trusted Application (TA) cannot partially execute a Task, an execution context of a Trusted Application (TA) is deleted between an executed Task and a subsequent command in an opened instance/session, a Trusted Application (TA) has to be Single Instance/Multi Session or Multi Instance/Single Session, said method running, inside the Trusted Execution Environment (TEE), each instance of a Multi Instance/Single Session Trusted-Server Trusted Application (TS) compliant to the TEE standard in an infinite state-full loop polling (SPi) a session of a Single Instance/Multi Session Trusted-Pipe Trusted Application (TP), the single session of each of the instances of the Trusted-Server Trusted Application (TS) being adapted to perform a task as a server, while said Trusted-Pipe Trusted Application (TP) being further polled (GPi) by the Customer Application (CA) and opening session depending on command coming from the Customer Application (CA), this polling mechanism making said Trusted-Pipe Trusted Application (TP) functioning as a mailbox for said Customer Application (CA) and said Trusted-Server Trusted Application (TS) to exchange data asynchronously, while accomplishing their respective tasks without blocking each other and enabling the Trusted-Server Trusted Application (TS) to request data within its currently executing task without stopping it. <EOS>