Message handling between domains

A method comprising:

• receiving, at a home controller of a home domain and from a first device in the home domain, a first message concerning a user device that is anchored to the home domain and that has roamed from the home domain to a visited domain;
• determining, by the home controller, that the first device is a router;
• in response to the home controller determining that the first device is a router:
• opening a tunnel between the home controller and a visited controller of the visited domain;
• and
• communicating the first message to the user device in the visited domain through the tunnel and the visited controller;
• receiving, at the home controller, a second message broadcasted by a second device in the home domain, wherein the second message concerns the user device;
• determining, by the home controller, that the second device is not a router;
• and
• in response to the home controller determining that the second device is not a router:
• generating, at the home controller, a response to the second message;
• and
• communicating, from the home controller to the second device, the response to the second message as a proxy for the user device in the visited domain.