There are also other workarounds to FISA courts including the “willful“ volunteering of information and tools (or else), using the NSA and their tools, and other foreign “friendly” collaborators like the Five Eyes, or German intelligence etc...
https://en.wikipedia.org/wiki/United_States_Foreign_Intellig...
https://en.wikipedia.org/wiki/Five_Eyes
https://www.dw.com/en/report-us-germany-spied-on-countries-f...
https://www.rt.com/usa/qwest-ceo-nsa-jail-604/
Here is some details on historical spying (a much smaller scale because of the smaller digital footprint)for the curious: