1-2 Chapter 1Introduction To SystemSIZE AND CONFIGURATIONThe iDCS 500 is a fully modular system comprised of a single cabinet configured as a Key Service Unit,up to two additional cabinets, interface cards and electronic keysets. A fully expanded system usingthe TEPRI cards can have a maximum of 352 lines or 360 stations. Without the TEPRI cards, themaximum number of lines is 208 and the maximum number of stations is 360. The maximumnumber of ports supported by the system is 488. Each cabinet of the system supports two powersupply units, the first of which must be a PSU-B and can support up to 56 stations. When assisted bya second power supply unit (either PSU60 or PSU-B) the cabinet can support up to 120 station devices.Both power supply units are connected to the DC bus for external battery backup. Each cabinet alsohas four (4) Digital Signal Processor (DSP) channels for use as DTMF receivers or tone detectors.Single Cabinet SystemA single cabinet system has nine universal card slots, a processor slot and two power supply slots, thefirst of which must be occupied by a PSU-B (see Figure 1–1). Station or trunk (line) cards can beinstalled in any of the nine universal slots. The TEPRI cards must be installed in slots 1, 2 or 3. Thisallows a maximum of 120 stations of any kind or 120 lines in a single cabinet system. Without usingTEPRI cards, the maximum number of CO lines in the basic KSU is 72.Figure 1–1 iDCS Single Cabinet SystemNOTE: The first power supply slot must be occupied by a PSU-B to supply sufficient power to all 10slots (9 universal and a processor slot) and support up to 56 stations. The second power supply slotcan be occupied by either a PSU60 or PSU-B. Do not use a PSU40 in either PSU slot.