As in previous designs, supervision of incoming calls is handled by relay sets known as "incoming trunk circuits". Unlike in previous designs, this work is also done in the trunk circuit for outgoing calls, so there are no junctor circuits. Since different outgoing trunks are connected to different places and are used for different calls, their relay sets can be specialized for a particular kind of signalling or call metering (see automatic message accounting) or other peculiarity. Thus a TSPS trunk can give complete control to an operator, while an E and M signaling trunk can do the kind of signaling required of a private long-distance line, while a local outgoing trunk can be simpler.