Sending commands to USB device

[Karolis Tamutis]

Hello, I'm trying to write basic drivers for my Motorola C650 phone,
based on moto4linux project. By default, phone is connected in AT
mode, guy from moto4linux simply sends "AT+MODE=8" to acm device to
change mode to p2k. I've tried same thing on ugen0, no reaction. Is is
not possible to send commands to device directly in a way of echo
"command" /dev/ugenX ? Thanks for your time.