DIFF Subgroup
H04M 1/70 Lock-out or secrecy arrangements in party-line systems
Introduced: September 1968
Full Title
Full titles differ between systems:
IPC:
Substation equipment, e.g. for use by subscribers > Circuit arrangements for preventing eavesdropping > Lock-out or secrecy arrangements in party-line systems
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) > Circuit arrangements for preventing eavesdropping > Lock-out or secrecy arrangements in party-line systems
No child classifications to compare. This is a leaf node in both IPC and CPC.