You will see this in Main Menu->Multiplayer when using shareware.
If you put your registered Quake on your phone,
this message goes away.

1. Shareware can only play the first 8 maps of the game. It cannot play any other maps.
2. Shareware cannot connect to a registered Quake game.
3. Registered Quake *can* connect to a shareware game!
4. If you have made a map with a map editor, you cannot run it with shareware Quake.