Confidence: Medium · Source: FCC ULS · As of 2026-09-14
N9NDU callsign genealogy
Currently held by OSTROWSKI, BRIAN 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 N9NDU's current licensee, walking backwards.
- Byerley, Joseph RINgranted 2018-02-16cancelled 2026-02-03
Successor callsigns
Callsigns held now by people who previously held N9NDU.
No current licensee on record previously held this callsign.
All historical holders
Every license row we've seen with the callsign N9NDU, oldest first.
- OSTROWSKI, BRIAN A IL1991-11-12 → cancelled 2003-11-13
- Byerley, Joseph R IN2026-02-03 active