When I tried to get the Telstra 7 Series MF636 modem working in Windows 7 I found that it would load the connection manager software but fail to find the sim/modem.
To get the modem to work I had to use the 'Safely Remove Hardware...' option to eject the ZTE modem which was registered as a USB drive as well.
Once the USB drive was ejected, the connection manager would then take around 5 to 10 seconds to recognise the sim and modem and then everything works fine.
