A data transfer system receives a first service flow, a second service flow, and a third service flow that comprise a data session for a user device. The data transfer system transfers the first service flow to a scheduler using a first data rate limit and transfers the second service flow to the scheduler using a second data rate limit. The data transfer system also transfers the third service flow to the scheduler. The scheduler schedules transfers of the first service flow and the second service flow at a higher priority than transfers of the third service flow. The data transfer system transfers the first service flow, the second service flow, and the third service based on the prioritized schedule and using a third data rate limit. Thus, the first and second service flows receive a limited amount of preferential bandwidth, and the third service flow obtains unused bandwidth from the first and second service flows, subject to the third data rate limit.