Confidence: Medium · Source: FCC ULS · As of 2026-09-12
NZ4O callsign genealogy
Currently held by ZIMMERMAN, CHARLES R
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 NZ4O's current licensee, walking backwards.
Successor callsigns
Callsigns held now by people who previously held NZ4O.
- GIELLA, THOMAS FFLgranted 2023-02-22
All historical holders
Every license row we've seen with the callsign NZ4O, oldest first.
- ZIMMERMAN, CHARLES R TN1997-01-23 → cancelled 2009-01-24
- GIELLA, THOMAS F FL2009-02-18 → cancelled 2013-02-15
- RADCLIFF, ERIC T TN2025-01-14 active