The Merlin (or sometimes known as all caps due to the stylized brand) was produced by AT&T (then American Bell) from 1983, and was continued to market via a rebrand the following year as AT&T Information Services, then the spinoffs of Lucent in 1996 then Avaya in 2000. The brand stuck around for nearly two plus decades, but the systems went more progressive. It’s not to say that the original line had a huge following and install base well into the new century. While there is no conclusive information of the research and development at this time of writing (early 2017), it was most likely developed to succeed the ComKey system at the time.
(As a sidenote, the ComKey was the first electronic telephone system, but it came with the price of complexity in wiring. ComKeys were basically a Peer to Peer or Point to Point, better known as P2P; system basically each set requiring fifty pair cables to connect to each other directly, or indirectly sharing the same telephone circuits; and while the system supported music on hold or paging, it required the similar shoebox sized KSU and circuit boards to do so.)
The Merlin replaced such complexity of the ComKey by
a) mandatory Touch-Tone dialing on the switch side, it supported rotary calling if trunks didn’t support it, or analog phones themselves. Some ComKey telephone sets had the option for rotary or Touch-Tone.
b) a fully electronic telephone switching system (albeit not fully digital)
c) the telephones using modular “four-pair” wiring (later known as “four wire”, one pair for analog, voice transmission, another “digital” for “signaling” the lamps, and another pair for power.) The wiring was not standard compared to other systems, due to debates on a digital wiring standard. (Newer phones from all manufacturers settled on using a single pair using pins 4 &5 if you used an RJ45.)
d) the ease of use to configure. Programming was simple as hitting the side switch to Program and press a few feature codes and press the button that you wanted a feature or line assigned. DIP switches were also found on the Merlin’s key unit for ring groups. It was very visual and straight forward Merlins did not have an internal clock, there was no PC involved, and could handle any disruption and;
e) The ability to “forklift” the system to a 1070, a System 25 or a System 75 PBX system, at the switching side but not on the desktop. That later mentioned expenses would be “protected” with telset support.
The original Merlin KSUs that went to the market were the 206, the 410 and the 820. Also were larger systems, the 1030 and 1070. In short the former single digit number indicated the support of trunks and the latter two digits of the model supported the “voice terminals”
The original telephones, err “voice terminals” are featured in the beginning, the 5 button set, the 10 button set, and a 34 button set. 34 button sets were typically used for secretaries and had speed dial, and one touch access to system features or other extensions they didn’t need to monitor with a “lamp”. Later versions introduced lamps for all 34 buttons.
The telephones themselves were very futuristic looking. The handsets had a radical shaped mouthpiece, replacing the “K” or “G” handset with a proprietary “R” shape (per to AT&T’s part catalog.) Another noticeable change for 1983, was the soft buttons. The only hard button was the dialpad, and all feature and line buttons used a tactical “membrane” key button, by basically pressing line number, phone number or name. Replacing the “desi” strips depended on the model because some slid in from the top and others was lifting a plastic on the very top of the telset.
Unlike the iPhone, the buttons were not heat sensitive, you could use a pencil eraser to activate a line or feature.
Merlin phones were not cheap. Some ranged from under $200 to $600. This didn’t include a $300 “adjunct” speakerphone or headset adaptor (“direct connect” would not be in the market till the early to mid 1990s. Such technology enabled the customer to use a plain ol RJ9 plug to the set, and the proprietary connector from that cable to the headset.) Even this time, the “phone” jack, the “1/4 inch” used for switchboards many years ago, that became the use of headphones; was still widely used. Regardless of the cost, the system had more features than the competitors. The cost benefit would be much lower due to the lack of needing to wire hundreds of wires together with the soon to be broken method of 1A2 systems.
There were improvements to the sets, a refresh occurred around 1987, when AT&T marketed the Built In Speaker (BIS) for the 10 button, 34 button and display based sets. This also was a replacement for the original sets that had that pesky one way speaker. This integrated device also changed the signature tactical buttons to hard buttons too, possibly to user’s frustrations with the button setup.