The AT&T Merlin - A 1980s Phone System in a Box

The AT&T Merlin Classic telephone systems were ideal for businesses big and small looking for a feature-rich, yet compact and easy to implement experience when compared to the 1A2 key systems that came before it.

At first, there were three choices depending on the size and needs of where it was to be used and how many inside and outside lines were necessary: the 206, 410, and 820. Different tiers of features were provided through the use of feature package cartridges, allowing a (mostly) seamless transition to a larger system if the need arose. Line switching was done at the control unit and not at the phone, like the 1A2 system, allowing for more compact and easy to implement installations and addons.

The early "breadbox" Merlin Classic systems were replaced with the Plus series, followed by the Merlin II and Legend, and eventually Magix Systems. The Merlin BIS-10, BIS-22, and BIS-34 phones (with the iconic handset mouthpiece and with or without membrane buttons) were compatible with the the Plus systems, and quite possibly the later models (though I can't say for sure, as I've only ever used the Classic, and for a short while, the Plus systems).

From time to time, I still see places of business using these old Merlins, but it's rapidly declining in favor of VoIP and hosted telephony systems. While still not a VoIP system by any stretch, this can be brought up to speed by using VoIP analog telephone adapters, which convert a SIP (or similar) IP phone service to POTS, allowing that old rotary or touch tone phone to make use of it, which is what I ultimately did after the local telco cut-off their copper POTS service after many years of stalling.

I've had my Merlin for almost a decade; hopefully, it lasts at least another. Parts & service aren't much of an option these days, so there's only a finite amount of "life" left in these systems.

Note: I wanted to go into much greater detail about the system, the handsets, and the accessories. The original uncut "tapes" amounted to around an hour and half's worth of footage. In the interest of brevity and not boring everyone with every last excruciating detail, this is the greatly abridged cut with most of the fluff and fat trimmed off. There's quite a bit that has been left out, but it was either that or have a a video that's way too long.

I may pick up where I left off in the form of a second video if there's enough interest.

Disclaimer: There may be factual errors, omissions, or other goofs. I'm not an expert on these systems or the ins and outs of telephone key and PBX units, just someone that enjoys giving one a new lease on life after being retired by its previous owner sometime in 2012. Much of everything discussed in this video was that which I picked up on during the past decade of my owning and using it. It's not a museum piece and is still in daily operation.

Chapters:
00:00 Introduction
01:46 Merlin 410 Control Unit
03:39 Feature Package Cartridges
07:50 Wiring
09:43 Handset or "Voice Terminal"
14:29 Voice Terminal Accessories
15:06 BIS-32 Operator's Phone
18:00 Basic Operation
23:24 Service Literature
25:34 Intercom "Signaling"
26:03 Crash Course on Programming
27:08 Pile 'O Paper (Manuals)
28:02 Personalized Ringers
28:57 Using Basic Analog Phones
29:45 Autopsy of a Basic Phone Adapter
30:33 Conclusion

Merlin Handset Colors Poster: https://commons.wikimedia.org/wiki/Fi...