Confidence: Medium · Source: FCC ULS · As of 2026-09-09
K4UDP callsign genealogy
Currently held by Treftz, Kristjan K
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 K4UDP's current licensee, walking backwards.
- Treftz, Kristjan KFLgranted 2009-11-17cancelled 2012-10-05
Successor callsigns
Callsigns held now by people who previously held K4UDP.
No current licensee on record previously held this callsign.