AT&T System 25 J58901A PBX Telephone Switch Cabinet 120V No Cards SD-66976-01

AT&T System 25 J58901A PBX Telephone Switch Cabinet 120V No Cards SD-66976-01

The AT&T System 25 J58901A is the main cabinet and card cage chassis for AT&T's System 25 small-business PBX telephone system. This unit is the core switching enclosure — it houses the backplane, power supply, dual cooling fans, and the 12-slot card cage that accepts the line, station, and control cards that make up a complete System 25 configuration. This cabinet is sold without cards; the card cage is empty and ready to be populated with the appropriate modules.

Specifications & What's Included

• Make: AT&T
• System: AT&T System 25
• Model: J58901A
• Part Number: SD-66976-01
• Power: 120V AC, 6 Amps, 60 Hz
• Power Inlet: IEC C14 with rocker on/off switch
• Cooling: Dual large internal cooling fans (front-mounted)
• Card Slots: 12-slot card cage — empty, no cards installed
• Rear Connectors: 12 numbered Amphenol 50-pin (Champ-style) connectors, slots 1–12 (CAB 2 labeling)
• Form Factor: Desktop cabinet
• Cards Included: None

Applications

The AT&T System 25 was a hybrid key/PBX telephone system introduced by AT&T in the mid-1980s and aimed at small-to-medium businesses needing between roughly 10 and 144 ports. It was a successor to the earlier Merlin system and could support a mix of proprietary AT&T digital and analog telephones as well as standard 2500-type analog sets. The System 25 used a modular card-based architecture: trunk interface cards, station cards, data module cards, and a processor card all plugged into the central cabinet backplane, making it field-configurable for a wide range of voice and basic data applications. This J58901A cabinet is the base chassis unit — purchasers sourcing replacement parts, building a complete System 25 from components, or repurposing the backplane enclosure for other uses will find this chassis useful. The System 25 was manufactured and supported through the late 1980s and into the early 1990s; this particular unit dates from August 1988 based on its manufacture date code. By the mid-to-late 1990s it was largely superseded by AT&T's (and later Lucent's) PARTNER and DEFINITY platforms, making working System 25 components sought after today for legacy system maintenance and museum/collector purposes.