Comment by solid_fuel

The NSA doesn't use a bunch of SIM cards on wire racks.

If the NSA needs outbound phone numbers, they're more likely to set up a shell company and pretend to be an MVNO or a VOIP telco provider, a couple computers on a cheap cloud host masquerading as a phone provider is a lot easier to manage and hide than a setup like this. This is a pretty common kind of business so it's easy enough to blend in, and it isn't restricted to a single apartment or city.

If the NSA wants to eavesdrop on phone calls, they just set up a room inside the relevant phone provider [0].

I think this is more likely a gang operation or a foreign influence operation. Details are thin but it feels like a shady organized crime operation (think quasi-legal, probably advertising as bottom-rate VOIP numbers or text gateways) that got used at one point by a foreign influence operation to make threats and try to interfere in domestic politics.

[0] https://en.wikipedia.org/wiki/Room_641A