Use your phone offline
In places where you do not want to make or receive calls, you may still access your calendar, contacts list, and offline games if you activate the offline profile. Switch the phone off when mobile phone use is not allowed or when it may cause interference or danger.
Press the power key 
, and select Offline.
When the offline profile is activated, your connection to the cellular network is closed. All radio frequency signals between the phone and the cellular network are prevented. If you try to send a message, it is placed in the Outbox folder, and is sent only when another profile is activated.
You can also use your phone without a SIM card. Switch the phone off, and remove the SIM card. When you switch back on, the offline profile is activated.
When the offline profile is activated, you can still connect to a WLAN to, for example, read your mail or browse the internet. You can also use Bluetooth.
Remember to comply with any applicable safety requirements.