An exemplary method and apparatus are provided for establishing a communication between a first communication terminal and a second communication terminal over a network. A server dynamically generates a first single-use key and a second single-use key respectively associated with the first and second communication terminals as a function of time data related to at least one previous communication between the first communication terminal and the second communication terminal, during a request to establish a call from the first communication terminal to the second communication terminal. The server compares the first and second keys that were generated, and authorizes the establishment of the communication if the compared keys are identical.