G06C—DIGITAL COMPUTERS IN WHICH ALL THE COMPUTATION IS EFFECTED MECHANICALLY
G06C27/00—Computing machines characterised by the structural interrelation of their functional units, e.g. invoicing machines
H—ELECTRICITY
H04—ELECTRIC COMMUNICATION TECHNIQUE
H04M—TELEPHONIC COMMUNICATION
H04M15/00—Arrangements for metering, time-control or time indication ; Metering, charging or billing arrangements for voice wireline or wireless communications, e.g. VoIP
H04M15/38—Charging, billing or metering by apparatus other than mechanical step-by-step counter type