Abstract: Two mutually independent clocks at a transmitting node and a receiving node of a routing network in a packet-switching telephone system are correlated by a synchronizing device associated with the receiving node whose processor, at the beginning of voice transmission between the two nodes, decodes a label of an incoming packet to determine its time of departure t.sub.s from the transmitting node whereupon a control unit at the receiving node adjusts the local clock in conformity with an estimated reading t.sub.x of the remote clock. This adjustment takes into account only fixed network parameters determining a minimum transit time for the packets by introducing a basic delay T.sub.d. After the correlation, an initial packet of a sequence representing a period of coherent speech --termed talkspurt--is stored for a time sufficient to augment the basic delay T.sub.d by a supplemental time lag T.sub.