http://personofinterest.wikia.com/wiki/QSOQSO is an amateur (ham) radio (or "Q") code used when one operator is making initial contact with another operator. The receiving operator typically responds with a greeting and a signal strength report before a longer conversation begins. Q-codes, like the better known ten-codes (10-4) used by citizen's band radio operators, are used to convey information using brief phrases. Once used widely by maritime, law enforcement, rescue, and aviation personnel, their use is now largely confined to military and amateur radio operators.