Wireless communication cost prediction for mobile device

A mobile device is equipped with a communications subsystem capable of wireless communication with a communications infrastructure using any of multiple different data-transfer services each with an associated cost. A service determination subsystem of the device uses a currently-active quality-of-experience profile to determine what service or services are to be used by the communications subsystem. A cost prediction arrangement is provided for predicting, on the basis of past data transfers involving the device, communication costs for the device to the end of a current usage period for at least one quality-of-experience profile used as the currently-active profile for future communications in the usage period. The cost prediction arrangement can be part of the mobile device or hosted by a remote system.