H04M 17/20 — IPC vs CPC Diff | Patent Classification Explorer

DIFF Subgroup

H04M 17/20

Full Title

Prepayment telephone systems (using a coded card to authorise calls from a telephone set H04M1/675)

Of 3 combined children, 0 exist in both systems.

3 codes are CPC-only extensions.

This code exists only in CPC.

Diff view requires codes present in both systems.