I can't configure USB 3G Modem (Prolink PHS300)

I have a PROLINK HSUPA PHS300 USB 3G modem. I can use it in windows XP/7/Vista/8. But recently about one year ago I upgrade my windows into Ubuntu. Now I am using Ubuntu 12.04 LTS 32-bit operating system. I have configured many USB Modem but I can't still configure it. When I put the modem into the slot and wait 20 secound after that the modems red light turn into green and after sometime the system shows "you are registerd to home network" and at the corner in Network Manager Applet it shows "New mobile broadband (GSM)" and I correctly setup step by step. But then I can't connect it to internet. I have configure wvdial but when I dial it shows "modem not responding"

The lsusb command shows in terminal:

steve@steve-Dell-System-Inspiron-N4110:~$ lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 003 Device 003: ID 04f3:0230 Elan Microelectronics Corp. 3D Optical Mouse
Bus 001 Device 003: ID 1bcf:2881 Sunplus Innovation Technology Inc.
Bus 002 Device 003: ID 0e8d:0023 MediaTek Inc.
Bus 003 Device 005: ID 19d2:1253 ZTE WCDMA Technologies MSM

and I have used gnome ppp and minicon and modem switch application but I cannot conncet the modem into internet but sometimes it connects from the Network applet bar but after disconnect no one can connect it again..

Please help me. I'm in danger if I cannot connect the modem I'll face a problem...........................