Abstract: Disclosed is a stored program, computer controlled telecommunications system including as its sole switching network an end-marked, multiple stage matrix network with a line side and a supervisory side. Almost all control functions including line scan and rotary dialed digit storage are included in the computer program, this procedure being possible due to the lack of need for any in-network controls. Certain peripheral circuits have appearances on both the line and supervisory side, these including an auxiliary loop usable as an overflow path providing added possibilities for completion of a path through the matrix network. The auxiliary loop is only called in on calls on which a speaking path has been established and on which the original path through the matrix network has been dropped during a change in the nature of a call.