Social Engineering
Couched in a more convincing spiel, leaving the poor bugger no option ...
Hello telco, this is GCHQ (honest guv). We urgently need to listen to those terrorists: they may be about to attack imminently. Yes of course they're terrorists: the Nether Blighty Sunday Cricket League is just a front! Yes, NOW, we can't wait while you complete all the red tape: that'll be too late, and your refusal to cooperate will be responsible for many deaths!