| 摘要 |
<p>A cost-efficient method that utilizes encryption techniques to prevent the unauthorized use of telephone customer calling card account and personal identification numbers (access codes), by electronic telephone network eavesdroppers and telephone company employees. The access codes are encrypted by the telecommunications carrier's access code collection device. The encrypted access codes are subsequently used instead of the clear-text access codes in all subsequent transmissions and subsequent processes that make use of access codes including billing and printing of calling card access codes.</p> |
