[aprssig] Station Callsign

[wa7skg]

In looking at my logs, I see some stations I can find no associated 
callsign for. One prominent example is VCAPK. Its position shows it 
hundreds of miles north of me which looks like it should be a bunch of 
hops. I thought these kinds of stations were limited to just a couple of 
hops to keep their information local. It is filling up my  messages log 
with telemetry information, about eight transmissions every 20 minutes 
or so. Another one is NPLNS which is sending a block of four messages 
twice every 10 minutes.

I guess my main curiosity is how these are beaconing without any 
reference to a callsign? I understand that digis can use aliases or 
tactical callsigns, but shouldn't they somewhere along the line be at 
least linked somehow to a valid amateur callsign?

Still learning,

Michael WA7SKG