AT&T Merlin

AT&T Merlin 5-button telephone (voice terminal) manufactured in early 1985

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 they were 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 2-line, 6-telephone (206), 4-line, 10-telephone (410), and 8-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).

Predecessors

The 1A2 Key Telephone System had the following problems which the Merlin System sought to solve:

• Complex electromechanical line switches in every telephone
• Each individual line pair plus control and light pairs must be run to each individual telephone, making for expensive on-premises wiring
• Telephones used point to point wiring which had to be hand assembled
• Control units consisted of many separate components including a power supply, line and feature module carrier, and punchblocks
• The above points made manufacturing and maintaining the system very expensive, especially by the 1980s
• Other than line switching, intercom, and hold, there was little possibility for modern features

History

The Merlin fixed these problems by:

• Having line switching done completely electronically at the Control Unit
• Using 4-pair wiring (two digital switching, one for analog and one for intercom)
• Telephones are now made with printed circuit boards and assembly is automated
• Fully electronic, all inclusive, one piece control unit
• Economical to produce and operate
• Slots for feature modules made possible features such as Speed Dialing, Automatic Line Selection, and Redial
• The Merlin telephones were also backwards compatible to the higher end enterprise systems, such as then System 75 and System 85 systems, then later Definity system, now called Communication Manager platforms.

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 90s 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.

A Merlin Legend system in an office building. There is at least electrical pin-compatibility between the Magix and the Legend, as a Magix DS1 board (colored grey) can be seen installed in this system.

In 1999, Lucent Technologies introduced the Merlin Magix as the replacement for the Merlin Legend. The Magix's carrier was metal and, as such, modules were not encased inside plastic shells as they were with the Legend. The Merlin Magix supported new 4400 series digital telephones as well as older MLX telephones, but it did not support the old ATL series telephones.

Due to declining sales and the introduction of the IP Office product line, Avaya retired the Magix on April 1, 2006.

The Partner system succeeded the small end of the Merlin system (206, 410 and 820) in the early 1990s. The final version of the Partner system, the Partner ACS, was introduced in 1990. Due to problems securing parts from distributors and the introduction of the Partner version of the IP Office, Avaya ended production of the Partner ACS on November 8, 2010.

Despite being over two decades old, the Merlin's modern electronic features and legendary Bell System era quality and durability still make the Classic Merlins very popular telephone systems with small businesses.

Merlin 206, 410, 820 Accessory Information

Cartridge Type I

Feature Package 1 (Available for use in Classic Merlin 206, 410 only):

• 5-party conference calling
• Ringer options
• Prevents outgoing calls on individual phones
• Privacy
• Automatic outside and intercom dialing
• Last number redial, automatic line selection, do not disturb
• On hook dialing, call transfer, hold reminder, group listening

Feature Package II (Included same features as Feature Package I plus the following)

• Personal and system wide 3 digit speed dialing
• Personalized Ringing
• Call pickup
• Group paging zones

Cartridge Type II

Music On Hold

• Allows a music source to be connected to the KSU which is heard by a caller on hold

Music On Hold/Paging

• Allows a music source to be connected to the KSU which is heard by a caller on hold
• Provides a paging system connection and music on hold to be used as background music while no pages are being made.

Cartridge Type III

Power Failure/Extra Alert

• Provides two RJ-11 jacks for standard touch-tone or rotary phone use in case of power failure.
• Extra Alert jack for external notification device.

References

• AT&T Sourcebook Catalog 1992, 1993, 1995.
• Merlin Installation, Programming & User Guides MERLIN 410: All Documents
• eOpinions.com on the Merlin Magix discontinuation
• Definity Enterprise Communications Server and System 75 and System 85 Terminals and Adjuncts Reference Manual December 1999, support.avaya.com