Patent ID: 7742460

Claim:
A method for detecting a malicious call, comprising: receiving, by a signaling unit, a first call request of a calling terminal; sending a second call request from the signaling unit to a called terminal device, the called terminal device operates according to a session initiation protocol; enabling a data transmission between the calling and called terminal device; transmitting user data between the calling terminal device and the called terminal device; receiving a detection request in order to detect the malicious call of the calling terminal, the detection request initiated by a user of the called terminal and formed according to the session initiation protocol; noting, by the signaling unit, an identifier for the calling terminal device; and storing the identifier permanently in a memory unit after receiving the detection request; wherein the called terminal device is a terminal device in a data packet transmission network, wherein the signaling unit performs signaling between the signaling unit and the called terminal device in accordance with the session initiation protocols, wherein the detection request is transmitted in an INFO message using the INFO method according to RFC 2976, and that a header section of the INFO message or a body section of the INFO message contains an information element which serves to uniquely identify the detection request.