NEC SPA-24PRTBA-B NEAX 2400 ISDN PRI T1 Card 23 Channel PA-24PRTB-A

NEC SPA-24PRTBA-B NEAX 2400 ISDN PRI T1 Card 23 Channel PA-24PRTB-A

The NEC SPA-24PRTBA-B is an ISDN PRI T1 trunk card designed for use in the NEC NEAX 2400 series PBX telephone system. It provides 23 bearer channels (B-channels) of ISDN Primary Rate Interface connectivity over a T1 span, allowing the PBX to interface directly with the public switched telephone network (PSTN) via a T1/PRI circuit. The board's PCB silkscreen identifier reads PA-24PRTB-A, and the slot faceplate label reads SPA-24PRTB A-B SP3029 B 13A.

Specifications & What's Included

• Manufacturer: NEC
• Model / Part Number: SPA-24PRTBA-B
• PCB Silkscreen: PA-24PRTB-A
• Compatible System: NEC NEAX 2400 PBX
• Interface: ISDN PRI (Primary Rate Interface) / T1
• Number of Channels: 23 B-channels (+ 1 D-channel) — standard T1 PRI configuration
• Data Rate: 1.544 Mbps (T1)
• ROM chips: Two STMicroelectronics M27C1001 EPROMs, labeled SP3029 B 13 (001 and 002)
• Main NEC IC: D72305CW (NEC Japan, dated 1986/1989)
• PCB manufacture: Made in Philippines
• Form factor: Full-size slot card / module for NEAX 2400 card cage
• Included: Card only — no manual, cables, or peripheral accessories

Applications

The NEAX 2400 is a large enterprise and carrier-class PBX platform that NEC produced from the late 1980s through the 1990s and into the 2000s. The SPA-24PRTBA-B T1/PRI trunk card is the interface between the NEAX 2400 switching fabric and an external T1 PRI circuit from a telephone carrier, enabling direct-inward-dialing (DID), inter-PBX tie trunks, and centralized voice traffic routing over a single T1 span. Each T1 PRI card of this type supports 23 simultaneous calls, making it a core capacity card in large multi-site enterprise deployments. These cards are typically sought by organizations that maintain legacy NEAX 2400 systems and need to replace failed or spare trunk cards, as well as by PBX technicians servicing installed NEAX 2400 infrastructure. The NEAX 2400 platform was widely deployed in large corporate campuses, hospitals, government facilities, and hotel properties throughout the 1990s, and many installations remained in service well into the 2000s.