Phantom Ciruits (1 gen 1921 anni – 31 dic 1921 anni)
Descrizione:
The switching of large numbers of calls was made possible through the use of phantom circuits. This allowed three conversations to take place on two pairs of wires.Aggiunto al nastro di tempo:
Data:
1 gen 1921 anni
31 dic 1921 anni
~ 12 months