47 CFR 32.2211: Non-digital switching.

(a) This account shall include:

(1) Original cost of stored program control analog circuit-switching and associated equipment.

(2) Cost of remote analog electronic circuit switches.

(3) Original cost of non-electronic circuit-switching equipment such as Step-by-Step, Crossbar, and Other Electro-Mechanical Switching.

(b) Switching plant excludes switchboards which perform an operator assistance function and equipment which is an integral part thereof. It does not exclude equipment used solely for the recording of calling telephone numbers in connection with customer dialed charged traffic, dial tandem switchboards and special service switchboards used in conjunction with private line service; such equipment shall be classified to the particular switch that if serves.