This network element enables the switching, adding and dropping of plesiochronous or synchronous signals on different layers. It enables the mapping of plesiochronous signals in synchronous tributaries known as virtual containers, and switching between these containers from the lower layer to the higher layer.

It should be made clear that this classification of network elements has been made purely for functional purposes. A single network element may be functionally configured in different ways by means of the control software it includes: An ADM, for instance, may also be set up as an LTMUX, and as has been seen, a DXC also has ADM functions.