!!! HELP !!! Problem with UNIX tip (cu) and modem

[xxxx]

	I have a MultiTech 224E modem connected to a Sun 3/50 ttya port.
	I have it set up so it will answer on the third ring, and
	saved this configuration in the non-volitile ram.  The problem
	is every time I dial a number using tip (or cu) the modem 
	resets it self to factory configuration, unless I turn it off
	and on (giving it the ATZ command also works). This is a pain in the 
	neck because I am using my office phone, and if I forget to reset 
	the modem it picks up the phone immidiately, therefore greeting the 
	caller with a high pitch tone! 

	My question is:	is there a way to tell the modem to reset itself
	(ie: give it the ATZ command) after the dialing, and also:
	what makes the modem go back to factory configuration?


	Thanks,   ssa