Anderson Jacobson
Model A 242A, SN=101733
A device onto which a telephone handset is placed to connect a computer with a network. The acoustic coupler might also contain a modem, or the modem could be a separate device.
Popular in the 1970s, acoustic couplers are no longer widely used. Nowadays, telephones connect directly to a modem via modular telephone connectors. This produces better connections than acoustic couplers and avoids the problems produced by irregularly shaped telephones.