"Following are the instances reported by the analysts where it was discovered that data was being sent to the Microsoft servers:
Text entered is stored in temporary files and an encrypted transfer is made once every 30 minutes to the following servers:
oca.telemetry.microsoft.com.nsatc.net
pre.footprintpredict.com
reports.wes.df.telemetry.microsoft.com
The analyst found 35 MB of data being sent to the servers after the web camera was turned on for the first time after Windows 10 activation.
It is further confirmed that the data from the voice port is indeed being transmitted even when Cortana is disabled. Over 80 MB of data is sent once every 15 minutes, when the computer is idle.
Folks at ArsTechnica also revealed similar results where they found that even with Cortana disabled, searching in Start menu sends requests to the Microsoft servers. It was further noted that Windows 10 sends data to servers related to One Drive when the service is itself disabled:
Windows 10 will periodically send data to a Microsoft server named ssw.live.com. This server seems to be used for OneDrive and some other Microsoft services. Windows 10 seems to transmit information to the server even when OneDrive is disabled and logins are using a local account that isn’t connected to a Microsoft Account. The exact nature of the information being sent isn’t clear—it appears to be referencing telemetry settings—and again, it’s not clear why any data is being sent at all."
http://wccftech.com/windows-10-privacy/