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DIFF Subgroup
H04M 1/20

Arrangements for preventing acoustic feed-back (H04M1/62 takes precedence)

Introduced: September 1968

Title

Titles differ between systems:

IPC: Arrangements for preventing acoustic feedback

CPC: Arrangements for preventing acoustic feed-back (H04M1/62 takes precedence)

Full Title

Full titles differ between systems:

IPC:

Substation equipment, e.g. for use by subscribers > Constructional features of telephone sets > Arrangements for preventing acoustic feedback

CPC:

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) > Constructional features of telephone sets > Arrangements for preventing acoustic feed-back (H04M1/62 takes precedence)

No child classifications to compare. This is a leaf node in both IPC and CPC.