Confidence: Medium · Source: FCC ULS · As of 2026-09-14
W5UM callsign genealogy
Currently held by McColloster, Michael B
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 W5UM's current licensee, walking backwards.
Successor callsigns
Callsigns held now by people who previously held W5UM.
No current licensee on record previously held this callsign.
All historical holders
Every license row we've seen with the callsign W5UM, oldest first.
- BORCHARDT, JOHN A IL1996-11-04 → cancelled 1999-12-13
- McColloster, Michael B LA2016-12-22 active