Among encrypted content (music data), license key, and copyright information, encrypted content has the most amount of data.
Users can freely copy encrypted content for themselves or send it to others.
With PHS mobile phones, for example, by using the transceiver function, you can copy music data with people registered as group members, without using any telephone companies.
You can listen to the copied data by simply purchasing a license key, which is a small amount of data.
This way, users can significantly reduce the data they need to download using their mobile phones (PHS).