The telephone network was designed with total trust for “network operators” who essentially have “root” to do anything.
This worked OK when the only operators were the various national phone monopolies (Cap’n Crunch notwithstanding), but today that level of access is much easier to get and abuse, and is difficult to trace.
There are efforts to bolt-on security to the telephone network but it’s really hard.
I think it’s more likely that (over the next handful of decades) the phone network fades into obscurity as more voice calls are connected over data links which offer much improved security models.
This worked OK when the only operators were the various national phone monopolies (Cap’n Crunch notwithstanding), but today that level of access is much easier to get and abuse, and is difficult to trace.
There are efforts to bolt-on security to the telephone network but it’s really hard.
I think it’s more likely that (over the next handful of decades) the phone network fades into obscurity as more voice calls are connected over data links which offer much improved security models.