Active callsigns include both current callsigns and callsigns that have expired but are still within the 2 year grace period. An amateur license is good (active) for 10 years. If the license is not renewed it "expires" however there is a 2 year grace period where the callsign is reserved and can be renewed. The ULS does not change the active status to expired until the grace period is over.
A callsign is cancelled in the ULS when a licensed operator changes callsigns. The old callsign is cancelled and is not available for reassignment for 2 years. A callsign can also be cancelled if the operator is SK. The cancel date is set to the date of death.
A callsign is considered expired if it was not renewed before the 2 year grace period ended. All expired callsigns in the ULS are available to be reassigned.
The FCC may terminate a license at any time. There is a 2 year period where the callsign is not available for reassignment. There are several reasons the FCC may terminate a license including violation of FCC rules. A license can be terminated simply because the FCC was unable to contact the licensee at the address listed in the ULS. It is very important to keep the contact address current in the ULS!
The ULS does not contain a record for every possible callsign. It only has data for callsigns that have actually been used. To overcome this limitation a list of all possible callsigns was created locally. This is the count of all the callsigns that do not have any records in the ULS.
This is the totals for each of the columns.
The FCC ULS database includes a number of amateur callsigns that are reserved for special functions or just simply not available for vanity callsigns. Since this site is interested in only callsigns that can be requested the reserved callsigns are not counted. Other people may include these reserved callsigns in their totals.
For more information on restricted callsigns please read the Restricted Callsigns web page for all the rules. The callsigns totals includes the count of callsigns that are restricted. This is subtracted from the total callsigns to give the total possible (all) vanity callsigns in the ULS. Since these callsigns are not available they are never included in any of the counts of available callsigns. Note: The counts do not include 1x1 callsigns at all. These are special event stations and the FCC does not manage these callsigns.