This was the period of invention, in which there were no experts and no authorities.

Telephonic apparatus consisted of makeshifts and adaptations.

It was the period of iron wire, imperfect transmitters, grounded circuits, boy operators, peg switchboards, local batteries, and overhead lines.
2.Development.1886 to 1896.

In this period amateurs became engineers.
The proper type of apparatus was discovered, and was improved to a high point of efficiency.

In this period came the multiple switchboard, copper wire, girl operators, underground cables, metallic circuit, common battery, and the long-distance lines.
3.Expansion.1896 to 1906.