Confidence: Medium · Source: FCC ULS · As of 2026-09-12
W1SJM callsign genealogy
Currently held by Mattern, Stephen J
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 W1SJM's current licensee, walking backwards.
- Mattern, Stephen JMAgranted 2013-12-03cancelled 2014-02-11
Successor callsigns
Callsigns held now by people who previously held W1SJM.
No current licensee on record previously held this callsign.
All historical holders
Every license row we've seen with the callsign W1SJM, oldest first.
- KAMINSKI, HENRY S MA1995-06-02 → cancelled 2007-06-03
- Mattern, Stephen J MA2025-09-11 active