I think I found examples of eight digit diable telephone numbers. Several ads in the NYT in 1947 had HOllis 5-10nnn numbers (HOllis 5- was in Queens, NY). Old Bell System literature says some large city exchanges could have as many as 10,500 lines--this was the maximum jacks within reach of an operator.
I was wondering how common this was in the US (presumably it was in big cities), and how long it lasted.
The Bell System developed the 'panel' dial exchange for big cities. It was designed to have more capacity and switch more efficiently than was possible with step-by-step gear; it utilized some basic common control circuits.
A key feature of panel was compatibility with the many manual exchanges a switch would connect to. For calls from manual exchanges to a dial exchange, operators had a keypad to enter the number quickly (either the originating operator or dedicated "B" operators* for that function).
For calls from dial users to a manual exchange Bell wanted the connection to be easy from the subscriber's point of view. Thus, dial subscribers dialed all their city calls regardless of the type of exchange they were calling--they did not have to know whether the called exchange was dial or manual. In this way it was easier to convert manual exchanges to dial.
To accomplish this, inward operators at manual exchanges had a display panel indicated the desired number. The display was controlled by the dial switch, which translated the called number into a signal to light the appropriate signal lamps.
The literature on this notes that a manual exchange could have up to10,500 lines (not merely 10,000). The display provided for this by having a leading fifth digit of 0 or 1. Presumably callers to such an exchange would dial eight digits.
(The inward operator display also accomodated the party line suffix letter, but that is beyond the scope of this discussion.)
So, would anyone know if eight digits were actually dialable in New York City or in other places, as the literature suggests? If so, how long did it last? I presume as preparations for DDD came along the eight digit subscribers got new numbers.
Thanks.*In large cities, manual switching required two operators--an "A" and "B" operator. The A operator answered the subscribers request. After the subscriber gave the number "Main 1234", the A operator would plug into the Main exchange where a "B" operator would take the call. The A girl passed the "1234" to the B girl, who made the final connection. Because in big cities most calls were out of the exchange all calls were handled this way. Early dial automation continued this pattern of A and B handling.