Confidence: Medium · Source: FCC ULS · As of 2026-09-12
AI4MD callsign genealogy
Currently held by Walder, Stephan
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 AI4MD's current licensee, walking backwards.
- Slezak, JanNHgranted 2021-11-10cancelled 2022-02-26
Successor callsigns
Callsigns held now by people who previously held AI4MD.
- Walder, StephanNCgranted 2025-11-20
All historical holders
Every license row we've seen with the callsign AI4MD, oldest first.
- Walder, Stephan SC2005-09-19 → cancelled 2006-01-10
- Slezak, Jan NH2022-02-26 active