The exchanges of domestic products are less important than they should be.
Subscribers to exchanges may also make arrangements to have all telegrams (except Press telegrams) ad - dressed to them delivered by telephone instead of messenger.
The territory in which a telephone administration operates is usually divided into a number of local areas, in each of which one or more exchanges are placed.
When the subscribers in a local area exceed a certain number, or when for some other reason it is not convenient or economical to connect all the subscribers in the area to one exchange, it is usual to divide the area into a number of districts in each of which an exchange is placed, and to connect these district exchanges together by means of " junction circuits."
In some cases the exchanges are connected together directly; but when the volume of traffic is not sufficient to warrant the adoption of such a course connexions between two exchanges are made through junction centres to which both are connected.