In Diplicity there are generally three types of press: Conference, group and private.
Conference is a channel where every nation in the current game is a member.
Private is a channel where exactly two nations participate.
Group is anything in between.
Unless the game was created with settings to disable on or more of the press types, any player can create, read and send to any channel where they themselves is a member.
Press messages will be tagged with the sender, and the time it was sent. Phase resolutions will be shown in the press log to clarify when they happened during the conversation.