Yes, but they have been bypassing due process by using 3rd parties instead of going directly to telecoms. And the friendly folks at Palantir et al are only too happy to share.
The due process is basically just a rubber stamped sham anyways — the only downside is that there’s a paper trail. But it seems that as a government agency you can just lie to the FISA courts to get your warrants and there won’t be any consequences later.