A communications system is provided, the system being operable to provide a communications session utilizing an internet protocol, such as for example IPv4, IPv6 and their extensions mobile IPv6 or IPv4. The system includes a mobile node having an application program and an operating system. The application program is operable to provide the communications session using an internet protocol address information. The operating system is operable to monitor the internet protocol address information and to inform the application program of a change of internet protocol address information. The application program is arranged to adapt the communications session in accordance with the change of internet protocol address information. As a result of the operating system informing the application program of a change of the internet protocol address information, the application program can adapt the operation of the communications session to reduce a likelihood of the communications session being affected when the IP address changes.