Abstract: An integrated switching and transmission of PCM words associated with channels and transferred on links utilizing the time-time switching principle is achieved by connecting an interhighway, i.e., a common time multiplex connection on which the PCM words are transferred in bus time slots, to inward and outward traffic memory arrangements each associated with one of the links. The memories store the words and in addition not only store, for each established connection channel, index numbers indicating the actual incoming and outgoing channel, but also a time index number indicating which bus time slot during an index read out phase is used for the connection. The phases are introduced in order to avoid the necessity of using memory access times corresponding to the bus time slots. Each phase comprises a number of bus time slots and each frame of the PCM words includes at least so many such phases as there are channels on each link.