AT&T Merlin

The AT&T (also Lucent, now Avaya) Merlin telephone system was introduced in late 1983, branded American Bell Merlin. After the breakup of AT&T in 1984, it was rebranded AT&T Merlin. It was designed at the beginning of the 1980s prior to the Bell System Divestiture as a modern electronic replacement for the dated electromechanical 1A2 Key System. Earlier Bell attempts at an electronic key system, such as the Horizon and Dimension, were not as successful as were the much larger systems, in fact the Dimension was a PBX. The Merlin was the first small electronic system, replacing the Com Key 416. The Merlin system was originally sold in two-line, six-telephone (206); four-line, 10-telephone (410); and eight-line, 20-telephone (820) configurations. Later, there was a further 10-line, 30-telephone configuration, with an expansion KSU allowing the system to accommodate up to 70 telephones available (1030 and 3070 respectively).

The 1A2 Key Telephone System and later ComKey series (4-16, 7-18, 14-34) had the following problems which the Merlin System sought to solve:

The Merlin System fixed these problems by:

The original Merlin was replaced with the Merlin Plus system in the late 1980s, using circuit cards to be expandable to 8 lines and 20 telephones, much like the original 820 model. The original Merlin Plus was dubbed the 820d. It was identical in features to the earlier Merlin 820 with the Feature Package 2 cartridge installed. Following the 820d was the 820d2. The 820d2 included the previous features as the 820d but featured an Automatic System Access (ASA) processor coupled with a voice synthesis capabilities and a Busy Buster. The ASA processor provided users with call forwarding, direct extension dial, and system answer capabilities. The busy buster allowed users to have the 820d2 automatically retry a busy number every minute for up to 10 minutes and notify the user when the call was connected. Both the ASA and Busy Buster required a their own voice terminal port to function. In the early 1990s, the Merlin II and Merlin Legend debuted with even more features and expandability, and new MLX telephones, but the system was also backwards compatible with the original Merlin telephones.

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