is
holding time includes not only the period while the subscribers are in
actual conversation over it, but also the periods while the operators
are making the connection and afterwards while they are taking it down.
It may be said, therefore, that the purpose of employing separate order
wires for communication between the operators is to make the holding
time on the trunks as small as possible and, therefore, for the purpose
of enabling a given trunk to take part in as many connections in a given
time as possible.

In outline the operation of a one-way trunk between common-battery,
manual, multiple switchboards is, with modifications that will be
pointed out afterwards, as follows: When a subscriber's line signal is
displayed at one office, the operator in attendance at that position
answers and finding that the call is for a subscriber in another office,
she presses an order-wire key and thereby connects her telephone set
directly with that of a _B_-operator at the proper other office. Unless
she finds that other operators are talking over the order wire, she
merely states the number of the called subscriber, and the _B_-operator
whose telephone set is permanently connected with that order wire merely
repeats the number of the called subscriber and follows this by
designating the number of the trunk which the _A_-operator is to employ
in making the connection. The _A_-operator, thereupon, immediately and
without testing, inserts the calling plug of the pair used in answering
the call into the trunk jack designated by the _B_-operator; the
_B_-operator simultaneously tests the multiple jack of the called
subscriber and, if she finds it not busy, inserts the plug of the
designated trunk into the multiple jack of the called subscriber and
rings his bell by pressing the ringing key associated with the trunk
cord used. The work on the part of the _A_-operator in connecting with
the outgoing end of the trunk and on the part of the _B_-operator in
connecting the incoming end of the trunk with the line goes on
simultaneously, and it makes no difference which of these operators
completes the connection first.

It is the common practice of the Bell operating companies in this
country to employ what is called automatic or machine ringing in
connection with the _B_-operator's work. When the _B_-operator presses
the ringing key associated with the incoming trunk cord, she pays no
further attention to it, and she has no supervisor