USB Modem Hang


I am using a Wavecom Supreme 20 USB modem through Linux (Embedded system). The modem is detected as /dev/ttyACM0.

On manually calling the chat script (/etc/ppp/peers/ppp0) using the command

$pppd call ppp0

the modem is able to dial and connect to the network (as ppp0). On rebooting the system (when the ppp0 connection is still alive), the modem stops responding and the modem requires a power reset to bring it back to working condition.

Has anyone come across such a scenario. Is there anything that I am missing. How do I reset the modem through software during boot sequence so that it works fine.

Thanks in advance,
V Karthick.