Teledyne Benthos ATM-900 and UDB-9400 series modem interface.
It's this easy:
import AcousticModem
modem = ATM900('COM1', 9600)
modem.write('Hello, World!')
# set remote modem properties
modem.remotePower(249, 3)
# Get modem properties like this:
modem.temp
# run the modem link test
print modem.linkTest(255)