Holmes was the first practical man who dared to offer telephone service for sale.

He had obtained two telephones, numbers six and seven, the first five having gone to the junk-heap; and he attached these to a wire in his burglar-alarm office.

For two weeks his business friends played with the telephones, like boys with a fascinating toy; then Holmes nailed up a new shelf in his office, and on this shelf placed six box-telephones in a row.

These could be switched into connection with the burglar-alarm wires and any two of the six wires could be joined by a wire cord.
Nothing could have been simpler, but it was the arrival of a new idea in the business world.
The Holmes exchange was on the top floor of a little building, and in almost every other city the first exchange was as near the roof as possible, partly to save rent and partly because most of the wires were strung on roof-tops.

As the telephone itself had been born in a cellar, so the exchange was born in a garret.