Phone phreaking got its start in the late 1950s in the United States. Its golden age was the late 1960s and early 1970s. Phone phreaks spent a lot of time dialing around the telephone network to understand how the phone system worked, engaging in activities such as listening to the pattern of tones to figure out how calls were routed, reading obscure telephone company technical journals, learning how to impersonate operators and other telephone company personnel, digging through telephone company trash bins to find "secret" documents, sneaking into telephone company buildings at night and wiring up their own telephones, building electronic devices called blue boxes, black boxes, and red boxes to help them explore the network and make free phone calls, hanging out on early conference call circuits and "loop arounds" to communicate with one another and writing their own newsletters to spread information.