There is a provided herein a proxy at a border between two transport domains, the proxy arranged to deliver packets to a communications device in a first transport domain; the packets received from a server in a second transport domain. The proxy is arranged to: receive a packet from the server, the packet directed to the communications device; and forward the packet to the communications device and reply to the server with a traffic handling offer message, the traffic handling offer message including a plurality of traffic handling options. The proxy is further arranged to receive a selection of a traffic handling option from the server; and apply the selected traffic handling option to packets sent from the server to the communications device via the proxy.