Why was it necessary to use the radio to send out information during World War II? There were already telephones at that time. Why couldn’t you just call if you had any information?

What a layman speaking in layman’s terms! Yes, there were telephones and wireless walkie-talkies during World War II, which were convenient for talking, but what if they were intercepted or eavesdropped by the enemy?

The telegraph was coded at the time, with a codebook. You could use clear codes or passwords, and the confidentiality was high.

The encryption of text messages and telephone transmissions was a follow-up method after the invention of computers after the war. High technology that emerged with the development of information technology,