KU4SP
Available2x2District 4
Competitive callsign — 1 application filed with the FCC.
License HolderCASTILLO, RENE R
License ClassAmateur Extra
Min. Class RequiredGeneral
LocationWYTHEVILLE, VA
Grant DateMay 24, 1999
Expiration DateOct 4, 2005
Cancellation DateFeb 13, 2001
Available for ApplicationsFeb 14, 2003
KU4SP is a highly sought-after 2x2 format amateur radio callsign. The license is currently held by CASTILLO, RENE R in WYTHEVILLE, VA. This callsign has attracted significant interest in the amateur radio community, with 1 vanity application filed with the FCC. The most recent was submitted by Springer, Philipp on Jul 31, 2026. KU4SP has 4 recorded FCC license history events.
CW & Voice Analysis
Morse Code
-.- ..- ....- ... .--.
CW Weight: 30 units(Light (fast to send))
Voice Phonetics
Kilo Uniform Four Sierra Papa
Readability: 7/10(Good readability)
This callsign is available now
Requires General license or higher to apply for this callsign format (2x2).
License History
- License CanceledFeb 13, 2001
- License ModifiedJan 31, 2001
- License ModifiedDec 21, 2000
- License ModifiedJun 10, 2000
Vanity Application Activity
Competing applications filed with the FCC for this callsign.
- Springer, PhilippFiled Jul 31, 2026Not awardedFCC ↗