Here's the earlier system mentioned, MF, shown in an operator training film.[1]
Two vertical rows of five numeric keys, plus the KP and START keys. Those tones were used within the long distance system, not out to customers.
The phone system started out entirely manual and slowly migrated to fully automatic over decades. Switching was automated before billing and routing. What you see in that video is an operator who is placing a long distance call for a customer. When this film was made, around 1949, local calls were mostly automatic dial, but long distance was only semi-automatic. The operator is doing the routing and billing. They have to find an idle outgoing trunk on their board to the next toll office along the route. Then they can use the keyboard to remote control that toll switch to connect them another step forward. When they get to the desired end office, which connects to customer lines, they can punch in the number of the final destination phone and complete the call. Lots of things can go wrong; hence all the different blinking light signals.
All this was gradually automated, before computers, using relays and special purpose hardware.
The phone system started out entirely manual and slowly migrated to fully automatic over decades. Switching was automated before billing and routing. What you see in that video is an operator who is placing a long distance call for a customer. When this film was made, around 1949, local calls were mostly automatic dial, but long distance was only semi-automatic. The operator is doing the routing and billing. They have to find an idle outgoing trunk on their board to the next toll office along the route. Then they can use the keyboard to remote control that toll switch to connect them another step forward. When they get to the desired end office, which connects to customer lines, they can punch in the number of the final destination phone and complete the call. Lots of things can go wrong; hence all the different blinking light signals.
All this was gradually automated, before computers, using relays and special purpose hardware.
Some background info:[2]
[1] https://archive.org/details/Operator1949
[2] http://atlantatelephonehistory.org/atlanta:part3