Exactly. If you wanted to get someone's attention, you make your signal something that would standout from all of the background noise. If someone send a RCPT signal back, then you could consider sending a more complicated signal.
Maybe the transmitter is located far away from their civilization's main location.
It should be a stronghold, just for comms, fully expendable, probably with no information in any local hard/soft/wetware about where they actually reside.
If we answer, we would be probably be talking to "a phone tapped to another phone"