Confidence: Medium · Source: FCC ULS · As of 2026-09-12
K4OSR callsign genealogy
Currently held by Roldan, Ernest A
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 K4OSR's current licensee, walking backwards.
- Roldan, Ernest ACOgranted 2019-12-16cancelled 2020-01-03
Successor callsigns
Callsigns held now by people who previously held K4OSR.
No current licensee on record previously held this callsign.
All historical holders
Every license row we've seen with the callsign K4OSR, oldest first.
- THOMAS, JOHN S FL1993-08-17 → cancelled 2005-08-18
- Roldan, Ernest A CO2020-01-03 active