A communication system is arranged to provide a communication service to a communication terminal. The communication system comprises a packet data network arranged to communicate data packets supporting the communication service to and from the communication terminal via a data path through the packet data network, a path computational element arranged to control the data path, an application server arranged to control the communication service and an internet multimedia sub-system operable to control the application server. The application server is operable to provide the communication service to the communication terminal in response to a registration request transmitted from the communication terminal to the internet protocol multimedia sub-system requesting an establishment of the communication service. When establishing the communication service, the internet protocol multimedia sub-system is operable to communicate an adaptation message to the path computational element including information indicating service quality parameters associated with the communication service. The path computational element is operable to calculate the data path in accordance with the service quality parameters and to adapt the packet data network in accordance with the calculated data path.