jan 1, 1919 - Rotary phones became available to the public.
Bell’s phone company, American Bell Telephone Company, began service of the rotary phone. Rotary phones were invented many years before this, but this was the “debut” moment for the general public. Before this people knew about the phones but not many people actually had access to them. This was a huge step for the telephone because it was finally going to be used for the practical use that it was meant for. People were actually able to purchase the phone and use it instead of just hearing about its progress.
Added to timeline:
The Atom vs the Telephone