Arrangements for interconnection between switching centres

Introduced: September 1968

Of 15 combined children, 5 exist in both systems.

7 codes are CPC-only extensions, 3 exist only in IPC.

Child Classifications

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H04M 7/0003 +2 CPC CPC only CPC only
H04M 7/0012 +3 CPC CPC only CPC only
H04M 7/0024 +9 CPC CPC only CPC only
H04M 7/006 +6 CPC CPC only CPC only
H04M 7/009 CPC only CPC only
H04M 7/0093 CPC only CPC only
H04M 7/0096 CPC only CPC only
H04M 7/02 for compensating differences of ground potential IPC only IPC only
H04M 7/04 for compensating differences of line impedance IPC only IPC only
H04M 7/06 using auxiliary connections for control or supervision +2 CPC IPC+CPC Available in IPC and CPC
H04M 7/08 for phantom working IPC+CPC Available in IPC and CPC
H04M 7/1 for two-way working, i.e. calls may be set-up in either direction over the same connection IPC only IPC only
H04M 7/12 for working between exchanges having different types of switching equipment, e.g. power-driven and step by step or decimal and non-decimal +1 CPC IPC+CPC Available in IPC and CPC
H04M 7/14 in systems involving main and subordinate switching centres IPC+CPC Available in IPC and CPC
H04M 7/16 in systems employing carrier frequencies IPC+CPC Available in IPC and CPC