A receiving node for receiving data packets in a packet communications system comprises a buffer for storing data packets received at the receiving node and for releasing the stored data packets to an application element of the receiving node. A buffer window defines a time period in which data packets are received at the buffer. A position of the buffer window is moved in time periodically, and a stored data packet is released when it is at an end of the buffer window. The receiving node further comprises a packet delay determining element for determining, for each received data packet, a delay of a received data packet by determining the difference between an estimated time of arrival of a data packet at the receiving node and an actual time of arrival of the data packet at the receiving node, a delay processing element for determining an average of the determined delays of a plurality of data packets and for determining when a change in the determined average is greater than a first threshold, and a buffer window adjusting element for adjusting at a first rate a position of the buffer window by a first amount dependent on the determined average of the determined delays and for switching to adjust a position of the buffer window at a second rate by a second amount dependent on the determined average when a change in the determined average is greater than the first threshold. The second rate is greater than the first rate.