CALEA spells out LI requirements. Anything CALEA covers, at least for investigations that have been closed, can be openly discussed. Intercepts using LI in the infrastructure are routinely introduced as evidence in trials. The spec docs might be FOUO, but LI capabilities are not a state secret.

Dragnet surveillance in cooperation with the NSA is a whole other thing. It might use some LI facilities, but, in many cases, LI specs for telecom equipment would not cut it for NSA purposes. Hence all the switches having LI capability and the NSA having their own cable taps and backhaul.