As to archives and comments of telephone number configurations, the prefix
> Zenith was used in the 1950's for non dial telephones in Pacific Palisades
> area of LA. Chicago had in the same period a 2L and 6N in some sub-urban
> area numbers in the same period. Not all possible combinations were used in
> all area codes, while several private NXX -- such as KRypton was used in
> Houston, Texas, for the Humble Building, and LT (WITH NO MEANING WAS USED
> UNTIL MODERN TIMES IN NYC.)
Zenith was used throughout the greater Los Angeles area for many years. It may have been used in other parts of the state.
When it was in use, I lived 20 miles east of Los Angeles in independent telephone company area and ZEnith was widely used to reach business in Los Angeles and such.