CREATE TABLE table_50342 ("Callsign" TEXT, "Area served" TEXT, "Band" TEXT, "Freq currently" TEXT, "Purpose" TEXT)

What is the Callsign in Brisbane with a Freq currently of 4rph?
SELECT "Callsign" FROM table_50342 WHERE "Area served" = 'brisbane' AND "Freq currently" = '4rph'
SELECT "Callsign" FROM "table_50342" WHERE "Area served" = 'brisbane' AND "Freq currently" = '4rph'