Author: Alan, 5B4AHJ
The JB prefix has not been used since 1963.
The JB8 prefix was used for a few days in August, 1963, by a DXpedition (JA1BRK/JB8, JA1HQG/JB8, JA1KHG/JB8 and JA1WU/JB8) to Torishima Island (not to be confused with Minami Torishima), and was also used in 1961-62 by JA7QQ/JB, also from Torishima Island (tnx JJ1WTL).
The JC prefix has never been used.
There are many callsigns with JB & JC prefixes in the Club Log QSO database. With the exception of the above JB calls in 1961-1963, these are all busted calls.
The majority of logged JB calls are busted YB calls, with a sprinkling of busted J6 & J8 calls.
Logged JC calls are busted JA, JH, JR, YC and other calls with similar prefixes.
Club Log maps these prefixes as follows:
JB8 - Japan from 1963-08-13 to 1963-08-18
JB - with the exception of the JB8 mapping above, all are mapped to INVALID for all dates
JA7QQ/JB - mapped by exception.
JC - INVALID for all dates.
From 2005, the /JI suffix has been used some Japanese Island DXpeditions, eg:
JI3DST/JI3 (11 February 2005), JI3DST/JI1 (July 27-30, 2012 etc.), JF0BPT/JI2 (August 8, 2008), JS6RRR/JI4 (May 20, 2007) etc (info from RX1AL)..