Different polling rates are applied to high priority BE service flows depending on whether the service flow contains, or is about to contain, traffic packets. A high priority service flow is identified upon boot-up of a user device, and defaults to a slow polling mode. A trigger causes the service flow to be serviced as a fast polling mode. The fast polling mode lasts for a predetermined period of time. If traffic continues at the end of the predetermined period of time, the predetermined period of time is reset so that the fast-polling mode continues until traffic flow on the high priority service flow ceases.