Playstation 3 Network allows you to communicate with other users in 3 ways: The first way is for you to send a text message to users using their Online ID. The second and third way is for you to communicate with them using audio or video capabilities. These 3 types of communication can happen on the playstation 3 Network outside of a game. Using the playstation 3 Network parental control settings to restrict these communications will keep sub accounts from using these features in the playstation 3 Network outside of a game. In-game communications are administered separately by game and may include audio and video chat, as well as text chatting (ie. instant messaging). Text chatting, or instant messaging, is game-dependent and can only occur in-game (not outside of a game on the playstation 3 Network). Using the playstation 3 Network parental control settings to restrict these communications in-game may result in the inability to play some games which depend on these communications for gameplay.

Source: Sony