Provided are methods and systems for estimating bandwidth in a communications network in which time slotting is occurring. A pre-filter is used to alter the distribution of transit deltas between data packets transmitted over the network to a receiver. By calculating the differences between arrival times of consecutive data packets received at a receiving end, and comparing the differences between the arrival times of the packets to the differences between corresponding send times for the packets, a determination is made as to whether such packets should be logically grouped together so as to constitute a single arrival event. The sum of the payload sizes of data packets within a group, together with timestamps for the arrival time and send time of the last packet included in the group is used as input to a bandwidth estimator.