This is a rare 8-button Ackerman-Boland interior telephone from 1908-1915 with a porcelain mouthpiece. Their sales catalog says, “The Company has for some years devoted itself zealously to the study, development and manufacture of interior telephones ranging in capacity from 2 - 25 stations.” Extremely good condition and very rare. The scan is from a 1906 Ackerman-Boland catalog.