Standby/Usage times - Ultimate Question!

HI,

the initial problem:

Standby and Usage times are the same.

For for a test - i set those settings:

1. Background refresh off.

2. Location services off.

3. Airplane mode on.

4. WIFI off.

5. Bluetooth off.

6. Closed all recent apps

7. Screen locked.

And still - Standby and Usage times are the same!

What could possibly be using my iPhone??

and yes - this happend even after restoring the iOS from iTunes and restoring backup,

and don't tell me there is an app working in the background - because the settings won't allow it - and there is nothing to work with! (No wifi, cell, BT, GPS...)

???