How to detect if phone has 3G enabled.

Some items in you applications you want to do some action only when there is 3G network (like video streaming upload or video calling.) So how to detect that phone has 3G network.

TBool isSupported = CFeatureDiscovery:: IsFeatureSupportedL (KFeatureIdProtocolWcdma);
if (isSupported)
   {
   // activate the service
   }