It is important to say that the IP you provided represents a machine inside your local network; most probably you have a modem/router which allows the connection of several devices, but have only one external (therefore internet VALID) IP, which is necessary to allow remote connections.
But here's the catch, usually these External IP's are dynamic, meaning that when the router is reset (or turned off), when it is turned on again the IP changes.
What you have to do is to set up a Dynamic DNS (you can see how here
http://howto.wired.com/wiki/Set_Up_Dynamic_DNS) and configure your router to port forward connections to the correct machine inside your network (now you should use the 192.168...... IP, and it is important that this IP is also not dynamic).
You will end up with an address that will be something like
http://mycalibre.hopto.org, which you must provide to the remote user for configuration.