Confidence: Medium · Source: FCC ULS · As of 2026-09-12
K4COO callsign genealogy
Currently held by VIRO, POLINA
The FCC publishes a previous_call_sign on
every amateur license — a self-link to the licensee's prior callsign.
Following those links produces the chain below.
Previous callsigns
Older callsigns held by K4COO's current licensee, walking backwards.
- VIRO, POLINASDgranted 2023-11-22cancelled 2024-01-20
Successor callsigns
Callsigns held now by people who previously held K4COO.
No current licensee on record previously held this callsign.
All historical holders
Every license row we've seen with the callsign K4COO, oldest first.
- SPENCE JR, JACK C FL2009-03-07 → cancelled 2021-05-06
- VIRO, POLINA SD2024-01-20 active