Hello deburat,
Bad news. What you are seeing is related to the feature described below. You will have to have the sign in information for the account on the phone or it will become useless to you.:
"Activation Lock for iPhone, iPad, and iPod touch" is a security feature, in part to deter re-selling of stolen devices. To learn more click here --> http://support.apple.com/HT201365
An activation lock can only be removed using information for the account that applied the lock. If you know this information follow the onscreen steps to enter the Apple ID and password used to set up the device, or enter the device passcode.
If you do not know the required information and you are not the original owner, get the owner of the account to remove the lock*, or return the device for a refund or recycle it. The device is otherwise useless to you. If the owner is unknown and has not provided contact information as a message showing in the login screen, there is no way to contact the owner unless the person who gave you the device knows them.