Take a look at CS_WANSample distirbuted with EMDK for .NET.   This sample uses the "C" TAPI call  lineSetEquipmentState() to enable or disable the radio.

Hi Alex, Also, you can use API functions from ossvc.dll:

GetWirelessDevices
ChangeRadioState
FreeDevicesList

With these functions you can control power state of all radio adapters (BT, WLAN, WWAN). details: http://www.codeproject.com/Articles/103104/Radio-Power

The attached symscript doc might be helpful. It enables keys to enable /disable all radios. with some keystrokes..it might be adaptable

Marcus, Thanks for your quick answer but unfortunately my customer needs to control the power state of the radio from a .NET application and the implementation you sent is not suitable for it. I found a C++ implementation on the C EMDK samples so I'll try to start from that one. If anyone else have a suggestion please advice. Best regards, Alex.