Can’t get my modem to answer

I’m trying to set up a Hayes Accura 56k speakerphone modem to answer calls when attached to remote download equipment. (For the sake of argument this could be taken to be a dumb terminal using RX/TX/GND cabling.)
I can set up the modem to answer when connected to a laptop running terminal emulation with full modem cable but it won’t answer when connected to the equipment mentioned first. I suspect this is due to an RI signal on the cable which in my case is obviously not being used.
Is there anyway to overcome the problem by hardwiring pins or using AT commands to change the answer options on the modem? Answer mode is already enabled and baud rate is appropriatlely set.