Confidence: Medium · Source: FCC ULS · As of 2026-09-12
WP4JO callsign genealogy
Currently held by OYOLA MARTINEZ, JULIO
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 WP4JO's current licensee, walking backwards.
- OYOLA MARTINEZ, JULIOPRgranted 2019-09-03cancelled 2019-09-21
Successor callsigns
Callsigns held now by people who previously held WP4JO.
No current licensee on record previously held this callsign.
All historical holders
Every license row we've seen with the callsign WP4JO, oldest first.
- ORTIZ, LUIS M PR1997-10-07 → cancelled 2009-10-08
- OYOLA MARTINEZ, JULIO PR2019-09-21 active