TDB.
You can use sysfs interface to control the modem.
You could look at
http://svn.gna.org/viewcvs/ueagleatm/trunk/ueagle-utils/monitor/daemon?rev=263&view=auto or
http://svn.gna.org/viewcvs/ueagleatm/trunk/ueagle-utils/debug/stats?rev=270&view=auto in order to see how to use it.
In sumary
/sys/bus/usb/drivers/ueagle-atm/*0/state = modem status
if you write a 1 in this file, you reset the modem.