I believe you are mistaken. This capability is in operation right now. The NSA captures 100% of the message traffic on the backbone network the storage required for transcribed voice is quite a lot less than for raw audio. That sort of monitoring began, at a smaller scale, back in the 1980s with “Tempest”.
You have to ask yourself:
WHY does Microsoft have so many huge DATA CENTERS all over the country??? Cloud operations
yes the nsa has been capturing 100% for a long time ...
my point .... due to constraints on processor speed , the MOUNTAIN of data still provides some anonymity ...
hiding in the crowd so to speak.
Soon that will be overcome.
Then we go real time ...everyone ... every where .. all the time