Patent ID: 7693269

Claim:
A method for identifying a caller for use in an Internet telephony system, the method comprising the steps of: receiving authentication information of the caller from a caller terminal; verifying the authentication information by using the received authentication information and a certificate of the caller, wherein the step of verifying the authentication information includes: extracting a public key for the caller from the certificate; dividing the received authentication information into signature data and a digital signature; and producing a hash value for the signature data; decrypting the digital signature by using the extracted public key; and comparing the hash value with the decrypted value to output an authentication result; and carrying out call setup if the verified authentication information and the certificate match, wherein the authentication information is generated by using a caller identifier and a private key that are applied by the caller, with no dependency on the caller terminal, and caller information corresponding to the caller identifier is transmitted to a callee terminal at the call setup.