originally, in the early 80s, 100 percent of all cross-exchange calls were listened to, without warrants. Basically, anything that went beyond a service area.
However, the tech at the time meant that most calls were not recorded, beyond the first few seconds, unless you used a trigger word or were on a list to be recorded.
This did mean no local exchange calls at the time.
Now the five data centers record a lot more than we admit.
And, yes, I said five.