If it's from Gray, I would expect to see an AE part number like LPB-, LPA, LPC, etc. The next two digits tell if it's prepay, post pay, semi post pay, etc. A prepay AE would be something like LPB-82-55. Normally the AE payphones (no subset required) would have an metal plate on the top portion of the housing, above the dial and before the advertising sign. The stamping will indicate the model number and hence how it will need to be wired.

L