CPC Subgroup
H04M 1/60 including speech amplifiers
Full Title
Substation equipment, e.g. for use by subscribers (subscriber services or facilities provided at exchanges H04M3/00; prepayment telephone coin boxes H04M17/00; current supply arrangements H04M19/08) > including speech amplifiers
5 direct subcodes
Child Classifications
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- H04M 1/62 Constructional arrangements