in today's lecture, we will explore the fascinating evolution of communication through the lens of the telephone, focusing on the importance of security in our digital conversations. as we delve into the topic, we'll discuss how, historically, the concept of a passcode was introduced to safeguard our messages, serving as a barrier to withdraw from unauthorized access. preadmission to sensitive information was strictly controlled, ensuring that only those who had the correct passcode could commence from the origin of the dialogue and participate in the exchange of ideas. this early adoption of security measures underscores the continuous effort to protect our communications, highlighting the passcode's pivotal role in the history of the telephone.