Discconect sierra 320U/313U

How can I disconnect the sierra modem after establishing connection (I’m using “direct IP” linux driver)?
I’m using the serial interface in order to connect to the ISP after establishing connection the modem is in data mode and I can not issue AT commands. (I tried to send +++ using chat application but the modem is still connected)


Since April 2013, all AirCard Mobile Broadband Devices are marketed, sold and supported by NETGEAR, Inc. Please consult support.netgear.com.