Radio check request on 6950 USB

[Treehouse SWL]

Around 2345 UTC (Oct. 20) on 6950 USB, I heard a guy repeatedly call for "Any station? Any station? ... Radio check, radio check, over" and give his call sign as "Charlie Alpha 271." He then would go silent for 20 seconds or so before repeating his request.

This went on for at least five minutes, still ongoing as of 2350 UTC.

Obviously, this isn't a ham call sign. Any idea what this is?

[autovon]

My guess is its a station that will be participating in the Noble Skywave exercise that starts soon.  CA271 is listed (Canada).
https://nobleskywave.ca/

6950 is one of the published frequencies too

[Treehouse SWL]

Ah, that makes sense - thanks for the info! The requests for a radio check ended around 2353 UTC.