Strange number card

[Adam]

This device is currently on eBay.  I know what the device is, it is for attaching a number card to the perch of a candlestick phone.

My question is, what is the text on the number card in this device mean?  Does anybody know what this text refers to, and/or why it would be installed on a telephone?

[GG]

My guess:  Some kind of intercom system or small manual switchboard, where a standard telephone was used in conjunction with a small jack-field.  Leaving the cord plugged into any of the jacks in the unit could prevent another station from being able to put a call through or reach the switchboard operator. 

I would guess 1915 - 1925 but I may be way off there.