Some good answers in this thread. I had the same question but I'm still a tad confused:

* I initially thought this meant someone in the WH network was using commercial proxies to appear as if they were exiting from a different network (which would align with "some user is firing up a proxy on their phone to exit in a different location")

* But then the description of residential proxies seemed to align more with traffic hitting an endpoint in the White House, and _exiting_ from the network there. But this didn't explain the timing (why isn't it 24/7).

* Finally it sounds like some person, legitimately on the WH network, has a device (cell phone, TV, whatever) that, when activated, is proxying outside traffic into the WH network.