Method and device for enhancing VOIP security by selectively scrutinizing caller's geographical location

1. A method performed by a network operator, for enhancing security of a Voice Over Internet Protocol (VoIP) call initiated by a calling device to a callee, the method comprising:

receiving a first message transmitted by the calling device, wherein the first message indicates that the calling device is initiating the VoIP call;

determining whether a scrutiny of the call is required;

as a result of determining that a scrutiny of the call is required, requesting the calling device's geographical location information;

receiving the requested geographical location information, wherein the received geographical location information identifies a stated geographical location of the calling device;

checking veracity of the received geographical location information to determine whether the call is suspicious, wherein checking the veracity of the received geographical location information comprises:

i) identifying a network node that received the first message indicating that the calling device is initiating the VoIP call;

ii) determining a geographical location of the network node; and

iii) comparing the geographical location of the network node with the stated geographic location of the calling device.

2. The method of claim 1 , wherein the scrutiny is required if the callee's profile includes an indication for enhanced VOIP security service.

3. The method of claim 2 , further including:

receiving a request to include the indication for enhanced VOIP security in the callee's profile.

4. The method of claim 1 , wherein whether the scrutiny is required is determined by analyzing a call detail record (CDR) of the caller.

5. The method of claim 4 , wherein the analyzing of the CDR determines that the scrutiny is required if calls placed by the caller have often been rejected by other callees and/or if calls placed by the caller lasted frequently less than a predetermined time interval.

6. The method of claim 4 , wherein the analyzing of the CDR determines that the scrutiny is not required if prior calls between the caller and the callee lasted longer than a predetermined duration.

7. The method of claim 1 , wherein

the first message transmitted by the calling device is a Session Initiation Protocol (SIP) Invite message, and

the step of requesting the calling device's geographical location information comprises transmitting to the calling device a SIP response message, and

the method further comprises receiving a SIP Update message transmitted by the calling device in reply to the SIP response message, the SIP Update message comprising a private header field comprising the geographical location information that identifies the stated geographical location of the calling device.

8. The method of claim 1 , further comprising:

if the call is suspicious, informing the callee before connecting the call, or rejecting the call.

9. The method of claim 8 , wherein the informing is achieved by at least one of:

forwarding the received geographical location information to the callee;

sending an audio message to the callee prior to connecting the call, wherein the audio message comprises one of a voice announcement or a ringtone; or

activating a warning signal detectable by the callee, wherein the warning signal comprises one of a warning displayed on a device of the callee or a display of the received geographical location information on the device of the callee.

10. A network operator device configured to enhance security of a Voice Over IP (VOIP) call initiated by a calling device to a callee, the network operator device comprising:

a receiver for receiving a first message transmitted by the calling device, wherein the first message indicates that the calling device is initiating the VoIP call; and

a processing unit that includes at least one processor, wherein the network operator device is configured to:

determine whether a scrutiny of the call is required;

as a result of determining that a scrutiny of the call is required, request the calling device's geographical location information;

receive the requested geographical location information, wherein the received geographical location information identifies a stated geographical location of the calling device;

check veracity of the received geographical location information to determine whether the call is suspicious, wherein the network operator device is configured to check the veracity of the received geographical location information by performing a process that comprises:

identifying a network node that received the first message indicating that the calling device is initiating the VoIP call;

determining a geographical location of the network node; and

comparing the geographical location of the network node with the stated geographic location of the calling device.

11. The network operator device of claim 10 , wherein the scrutiny is required if the callee's profile includes an indication that an enhanced VOIP security is required.

12. The network operator device of claim 11 , wherein the processing unit adds the indication in the callee's profile upon receiving a request.

13. The network operator device of claim 10 , wherein the processing unit determines whether the scrutiny is required based on analyzing a call detail record (CDR) of the caller.

14. The network operator device of claim 13 , wherein the processing unit determines that the scrutiny is required if analyzing the CDR reveals that

caller's calls have often been rejected by other callees, or

the caller's calls have lasted frequently less than a predetermined time interval.

15. The network operator device of claim 13 , wherein the processing unit determines that the scrutiny is not required if analyzing the CDR reveals that prior calls between the caller and the callee lasted in average longer than a predetermined duration.

16. The network operator device of claim 10 , wherein

the first message transmitted by the calling device is a Session Initiation Protocol (SIP) Invite message, and

the network operator device is configured to request the calling device's geographical location information by transmitting to the calling device a SIP response message, and

the network operator device is further configured to receive a SIP Update message transmitted by the calling device in reply to the SIP response message, the SIP Update message comprising a private header field comprising the geographical location information that identifies the stated geographical location of the calling device.

17. The network operator device of claim 10 , wherein if the call is suspicious, the processing unit informs the callee before connecting the call, sending a rejection message to the caller, or not connecting the call to the callee.

18. The network operator device of claim 17 , wherein the network operator device informs the callee that the caller is suspicious by at least one of:

forwarding the received geographical location information to the callee;

triggering an audio message prior to connecting the call; or

activating a warning signal detectable by the callee.

19. A method performed by a network operator for enhancing security of Voice Over Internet Protocol (VoIP) call from a calling device operated by a caller to a called device operated by a callee, the method comprising:

receiving a first message transmitted by the calling device, wherein the first message indicates that the calling device is initiating a VoIP call;

receiving a second message transmitted by the calling device, the second message comprising first geographic location information, the first geographic location information identifying a stated geographic location of the calling device;

identifying a network node that received the first message indicating that the calling device is initiating the VoIP call;

determining a geographical location of the network node; and

comparing the stated geographic location of the calling device with the determined geographical location of the network node to determine whether the caller is suspicious; and

as a result of determining that the caller is suspicious, transmitting a call rejection message to the calling device or informing the callee that the caller is suspicious, wherein

obtaining the second geographic location information indicating the actual geographic location of the calling device comprises obtaining network node information identifying the actual geographic location of a network node that received the first message indicating that the calling device is initiating the call.