UPDATED MAY 2015
The operator switchboard (or Attendant Console) dates back to the same look essentially since 1984, first released for the System 75 PBX.
This model the 301 Series. This was the very original console used for the System 75, originally designed for handle a few hundred of extensions.
Later models became the 302 series (not to be confused with a 1930s style telephone produced by the same company, but rarely is branded as such, only in the administrative terminal sessions to add stations and alike.) The difference between the 301 and the 302 is additional indicator “lamps” near the dialpad, to alert operators of alarms, major alarms such as trunk outages, to notify of other console positions are open for calls, etc. Another difference between the 301 and the 302 is the display had no softkeys or space to press additional features (this got moved to the lower on the console.)
The 302 Series was available since the late 1980s at the earliest. Over the years there were 4 different versions of 302s, suffixed with letters
302A was the model shown below, very Merlin looking, and used button caps similar to Nortels, but more smaller. Simply it was a modified version of the 301 console released in 1984.
302B had a different display, with a white or black instead of metallic. This version was likely in general availability in the early 1990s. This version had options for 2 or 4 wire environments, however you had to specify because boards inside were designed for one or the other not both.
Both 302A and 302B (and most likely the 301) had used 1/4″ phone jacks for the hand or headset. The console did not function until that piece was plugged in. The operator would then log in, and the console would be in function. When the operator would be done for the day, the console would automatically log out and go to idle mode when the operator unplugged the plug.
302C, released during the Lucent years replaced the button caps to a large letter-sized desi strip with a plastic overlay. Another key improvement was it supported 2 or 4 wiring environments, and was interchangeable. Prior to 302C, you had to specify which version if you needed the full 8 wires of copper to connect the console or two wire. (It should also be noted that despite the single pair of wiring, one needed power. On RJ45 jacks, pins 4&5 provided the DCP tip and ring and 7&8 pins provided the set’s power.)
C also introduced modular connections for the hand or headset, which changed the way the set would go idle or login. The intention of the 302C was to have the head or handset remain stationary at all times. Because of the change of jacks, the operator would had to press a few buttons to log them in, because the intention was the RJ11 jack would stay stationary.
302D was introduced around the turn of the century and required 2 wire environments only. 302C could work in ether/or environment, and not like the 302B which needed to be ordered by AT&T or Lucent the specify environment. As mentioned the set’s tip and ring is 4&5 and external power for pins 7&8 on an RJ-45 plug, this explains why RJ45 plugs are used even when it can use an RJ-11. The reason for this is only because the circuit board requirements that dictates the 2-wire digital line card for the console to work, not the system itself.
At some point, as of this writing in 2015, the 302 Series is officially dead and is no longer sold as new by Avaya as many operators have evolved to administrative assistants doing multiple things and split the calls between those groups, or in some operator environments have been replaced by software based sets. Operator sets don’t come cheap, and including its Direct Extension Selection or DXS can cost about $1,100 new!
The DXS has evolved, but the general idea hasn’t changed. In fact the Merlin looking industrial designe remained in tact right to the EOS. The first generation had 8 buttons on the very bottom acting as “Hundreds groups select”. Simply put, if you have dial plan from 4000 to 6000, the bottom 8 buttons would be labeled “40”, “41”, “42” and “53”, “54”. etc. So if you want to call extension 5138, you would hit the bottom “51” key from hundreds group, then press “38” in the 100 array keys. You can monitor a group of hundreds at a time and in later models as the System 75 evolved from supporting a few hundred extension into the behemoth of the Definity PBX supporting tens of thousands of lines, the Hundreds group keys maxed to 20, so you could monitor a couple thousands of lines if you had that model.
This picture is interesting because its very rare for any AT&T/Avaya Red publication to show exploded views of any of their equipment. This was standard operating procedure for Nortel if someone wanted to replace a part in a console or a set, however it was the job of AT&T to Lucent to Avaya to let this type of work be done by them or vendors.