4. The method of claim 3 , wherein the biometric signature assigned to the pre-determined VoIP phone number is generated based on another speech data of the owner obtained during a training period, wherein one of language and content of the speech data and the another speech data are different.
3. The method of claim 2 , wherein the speech data is extracted from a phone call conversation of the speaker originated from a pre-determined voice over Internet protocol (VoIP) phone number, the method further comprising: assigning a biometric signature of a owner of the pre-determined VoIP phone number to the pre-determined VoIP phone number; determining in real time that the speaker is not the owner of the pre-determined VoIP phone number when the biometric signature of the speaker mis-matches the biometric signature assigned to the pre-determined VoIP phone number.