AT&T Merlin Mail MM04 Release 2 Voicemail System 4-Port 4-Hour 115V

AT&T Merlin Mail MM04 Release 2 Voicemail System 4-Port 4-Hour 115V

The AT&T Merlin Mail MM04 is a standalone voicemail system designed to integrate directly with AT&T Merlin PBX telephone systems. Running Release 2 firmware, it supports up to 4 analog phone ports and provides up to 4 hours of message storage capacity. The gray metal enclosure houses all processing and storage internally, connecting to the Merlin key system via standard analog line interfaces.

Specifications & What's Included

• Brand: AT&T
• Model: Merlin Mail MM04
• Release / Version: Release 2
• Comcode: 406467902
• Number of voice ports: 4
• Message storage capacity: 4 hours
• Power input: 115V AC, 50/60 Hz, 4A; or 230V AC, 50/60 Hz, 2A
• Rear connectors: IEC AC inlet, IEC AC outlet, cooling fan
• Side/port panel: 4 analog phone ports (labeled 1–4) with status LEDs, DB25 parallel connector, DB9 serial connector
• Additional connectors: DB25 parallel, two DB9/DB15 serial ports, two mini-DIN (PS/2) connectors
• Power rocker switch on rear panel
• Form factor: desktop/wall-mount enclosure
• Unit only — no cables, documentation, or mounting hardware included

Applications

The AT&T Merlin Mail system was designed specifically for use with AT&T Merlin key telephone systems, which were widely deployed in small to mid-sized businesses throughout the late 1980s and 1990s. The MM04 served as the dedicated voicemail processor for Merlin PBX installations, handling automated attendant functions, individual mailboxes, and message retrieval for up to 4 connected phone lines. These systems were a common fixture in offices running AT&T Merlin, Partner, and related key system platforms. Today the MM04 is primarily sought by businesses or technicians maintaining legacy Merlin PBX installations, or by collectors of vintage AT&T business telephone equipment.