identify stop recongnizing the cell phone 7610

[address@hidden]

Hi, I am using gnokii with Nokia 7610 everything working fine and we are 
plaining to use gnokii mainly for sending nagios notifications. 

There is one 
problem that after sometime (hour or two) sending SMS stop working and at the 
same time the "gnokii --identify" command stop to recognize the cell phone 
connected at  /dev/ttyACM0

sendsms/identify start working after unplug/plug 
cell phone usb cable.

Any idea why we its require us to plug/unplug the phone 
cable so often, any suggestion will be highly appreciated to make the 
connection stable coz it will be used to send notifications of problem with 
your network hosts.

Thanks. 

Askar.