Call signs are available by call sign, by date(s) assigned for use. Call sign assignment is subject to availability, per reservations/assignments made as appearing in the 1x1 Call Sign Database.

The 1x1 Special Event Call Sign Coordinators shall ''coordinate, maintain and disseminate a common database of amateur station special event call signs.'' The five FCC appointed Special Event Call Sign Coordinators maintain a shared 1x1 call sign database so that both requesters and coordinators will know which call signs are available at any given time.

The FCC says that special event 1x1 call signs are authorized for use "in conjunction with an event of special significance." This suggests an event with high public visibility, as opposed to a routine ham radio contest or other operating event. However, a special event call sign could be used in conjunction with a contest if one were to occur within the call sign reservation period.

The five special event call sign coordinators have the authority to determine if a request is in keeping with the intent of the special event call sign system. Any licensed amateur may request a special event call sign. Call signs may be requested up to one year in advance of their use on the air. Call signs normally will be granted for periods of 15 days or less. Because of the limited number of call signs available, requesters are encouraged to limit their requests to the duration of the special event.

A block of 750 call signs is available for use in the special event call sign system. The format of each 1x1 call sign consists of a single letter K, N or W prefix followed by a single numeral, 0 through 9, followed by any single letter except the letter X, which is not available to amateur stations.