“This iPhone was lost and erased. Sign In with the Apple ID that was used to erase the iPhone” is the message that appears if an iPhone has been locked via iCloud. A new way to bypass icloud activation for iOS 8 has emerged and allows you to unlock any iPhone with iCloud Activation lock. This is helpful when you need to access your iPhone “find my iphone” feature  Similar messages like “Your iPhone is currently linked to Apple ID. Sign in with the Apple ID that has been used to set up this iPhone”.