content: Just guessing here... On Android:   It asks for the phone identity because your phone number becomes your username. It asks access to your contacts list because it searches for contacts who also have Telegram. It asks to read SMSes because in this way it can read the activation code automatically the first time you set it up. It asks access to your camera to let you take photos and videos and share them with your friends. It asks access to your microphone because it lets you send voice messages. It asks access to your GPS position because it lets you share your position with your friends. It asks access to your storage to store the pictures and videos that you received from your friends. It asks full network access because of course it uses Internet. It asks to start at boot so that it can receive messages even if you never started it. It asks to have access to vibration because this is how it notifies you of messages and events. etc.