Olivetti LINEA office Guide Rapide page 53

Connection Case 1 Switzerland
Connection Case 2
Insert the connector or plug of the additional device into the socket (see the related illustration).
A = telephone line input (LINE IN)
B = wall socket for telephone plug
C = external telephone, with or without adapter, telephone answering device (EXT)
D = socket for external telephone, telephone answering device or other unit.
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