What is a PBX simulator good for?

[gooseEL34]

Got a lot of parts (I like metal enclosures and build guitar effects into them after gutting).
Got a Micro Seven LS100 Mini-PBX Simulator. 

Any idea what this does....a google search got me to the Micro Seven webpage, but it went over my head?
I am assuming some kind of telephone line quality tester....

No knobs.  Essentially a power cord and 2 telephone jacks on the back with one red led (on hold/busy) and one trimpot (line level) on each....

Reading the site, I "think" you plug a phone into it and by punching in phone numbers and pound sign codes, you can get various responses.

Interesting?

[nctnico]

It is a public exchange simulator. Probably to make phone calls between two devices without having to pay phone costs.