James;
I can't say that I have heard of an A-2225 transformer from Etone or ever seen a need for an "audio transformer" in an Executone elevator application. I will say that the Valcom stuff is pretty straight forward & will only need -24VDC power supplies & some connection to an audio path to the phone system (typically connected to a C.O. port in the phone system).

You said that the transformer is used in 2 places so my first guess would be for the power supplies for the Valcom but if thats not the case it might be hooked up to an auto dialer used to dial an external number (I.E. 911, security) in the event that the elevator button is pushed.

All of this id strictly speculation so if you have a picture I might be able to figure it out.