best approach to resurrect an old call centre LED message sign

I bought an old programmable ‘call waiting’ message sign from a call centre and would like to get it working as a network dynamic display.
Any advice would be greatly appreciated as this is quite a bit outside of my experience.

Interface ports are unusual - phone sockets. Is this likely to be some serial variant? If so, is there any easy way to identify the pins without trial and error? I can wire via a 6 pin phone cable to DB9 if that is likely to work.
It seems to be related to the signs discussed here, since it shows SDX ACD on boot, although it has an Intel processor rather than Spectrum:

If this approach is a no-go, what would be necessary to use an Arduino to run this?
I see a number of MAX7219ENG LED driver chips and CD74H04E chips, which are apparently things called ‘High Speed CMOS Logic Hex Inverters’.
Lots of clearly labeled 5V outputs so I think directly powering the Arduino would not be a problem.

more photos

Any pointers would be appreciated - not sure where to go at this point...

If it uses MAX7219s, you have it licked. Find the connections and use the "parola" libraries.

Thank you for responding. If it's relatively straightforward then I'm happy to ignore the existing setup.

Other than power, there are 2 sets of 6 wires, one from either side of the display, going to the mainboard.
Is this likely to mean that there are 2 matrixes per side - 3 wires each?
If so, can the parola library handle multiple matrixes on different pins?

I can find a lot of mention of virtual matrixes but nothing regarding that.

My mistake. It has 7 wires going to a cmos inverter (CD74HC04E) on each of the 2 display matrixes. This chip goes on to the MAX7219s.

The MAX7219 is a bit like a shift register; it has a data in, clock in and CS line, with a data out to daisy chain to the next. So basically three wires would be enough to control the whole thing.

If it was the intention to use it as two-line display, I can imagine they use two separate sets. Then one set of three would control one line, the other set of three the other.

The inverter is most likely there to clean up signals and get rid of noise before passing it on to the MAX7219s.

I'd say get the MAX7219 library, load it up, wire it all up, and see what happens. You may have to invert signals yourself, unless they're using two inverters in series so the signal to the MAX7219 is in the end not inverted.