Confidence: Medium · Source: FCC ULS · As of 2026-09-12
AI4DM callsign genealogy
Currently held by Frederick, Thomas C
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 AI4DM's current licensee, walking backwards.
- Mathews, David SFLgranted 2014-06-03cancelled 2015-01-09
Successor callsigns
Callsigns held now by people who previously held AI4DM.
- Frederick, Thomas CFLgranted 2024-09-07
All historical holders
Every license row we've seen with the callsign AI4DM, oldest first.
- Frederick, Thomas C FL2004-01-12 → cancelled 2004-05-28
- Mathews, David S FL2025-01-09 active