In a hierarchical synchronization method for a telecommunications system employing message-based synchronization, in order that a node can recover from the loss of synchronization: (a) a list is formed for each mode interface unit from the group of interfaces appropriate for synchronization in such a way that of the interfaces connected to neighboring nodes, the list only comprises interfaces connected to a neighboring node which, if selected as the node timing source, does not change the synchronization signature transmitted by the node, (b) the node interface units monitor the operation of the control unit of their own node in order to detect whether the node has lost its control unit, (c) if a synchronization signature received by an interface on the synchronization list changes in such a way that the node outgoing signature should be changed and that change occurs when the interface unit has changed and that change occurs when the interface unit has detected the loss of the node control unit, the interface unit informs the other node interface units of this change, and the interface units thereby delete this interface from the group of interfaces appropriate for synchronization, and (d) if all interfaces are deleted from the group of interfaces appropriate for synchronization before the interface units have detected that the control unit is restored, the interface units start using another failure situation procedure.