Patent classifications
H
ELECTRICITY
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H04
ELECTRIC COMMUNICATION TECHNIQUE
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H04M
TELEPHONIC COMMUNICATION
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3/00
Automatic or semi-automatic exchanges
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H04M3/42
Systems providing special services or facilities to subscribers
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H04M3/50
Centralised arrangements for answering calls; Centralised arrangements for recording messages for absent or busy subscribers; ;; Centralised arrangements for recording messages
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H04M3/53
Centralised arrangements for recording incoming messages; , i.e. mailbox systems
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