Some approaches , such as that adopted by the Sonork enterprise IM software or the Jabber\/XMPP network or Winpopup LAN Messenger , allow organizations to create their own private instant messaging network by enabling them to limit access to the server ( often with the IM network entirely behind their firewall ) and administer user permissions . Some approaches allow organizations to deploy their own , private instant messaging network by enabling them to restrict access to the server ( often with the IM network entirely behind their firewall ) and administer user permissions .