Lately the local books around here have dropped from full size and they are 7 x 9 1/2 now.

Central telephone Company before being taken over by Sprint in the mid 1990's. Old Exchanges: DUdley 2,4 and EVergreen 5

But reading and remembering, this will throw a wrench into that location or two company theory:

0 none (on some telephones, "OPERATOR" or "OPER")
1 none
2 ABC
3 DEF
4 GHI
5 JKL
6 MNO
7 PQRS (on older telephones, PRS)
8 TUV
9 WXYZ (on older telephones, WXY)

Are you ready? DU = 38 and EV = 38

DUpont 5 became EVergreen 5

That was fun!