The Model 590B consists of 5 pairs of solid-state closures. These closures may be used to switch microphone or line level audio signals, as well as low voltage DC signals. The Model 590B features built-in logic programs. These programs are selected via an on-board DIP switch. The logic programs include a first-come, first served (Lockout) program, an all-call program, and an independent program. Typical applications would be paging system control where multiple paging stations are present, or program selection from remote locations. The Model 590B may be linked, to create larger switching systems. It may also be used in conjunction with the Model 697B, to create additional program functions.