On radio conversations, one says "roger that, wilco." 'Wilco' is short for "will comply". But where does 'Roger' come from?

I went to google and typed +roger +"radio terms" and found the following response:

Why do people say "Roger" on the CB to indicate that they understand?
Beth
Orlando, Florida

Dear Beth:
"Roger's" origins are actually pretty simple. According to the mammoth ham radio resource AC6V's Amateur Radio Reference Guide, the letter "R" has been used since the early days of Morse Code to indicate that a message has been "received." The voice code equivalent for "R" is "Roger."

You may have also heard the phrase "Roger Wilco" in various military-themed movies. "Wilco" is radio slang for "Will Comply." (It's also a great rock band).