Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Publication of BE424243ApublicationCriticalpatent/BE424243A/xx
H04M9/00—Arrangements for interconnection not involving centralised switching
H04M9/001—Two-way communication systems between a limited number of parties
H—ELECTRICITY
H04—ELECTRIC COMMUNICATION TECHNIQUE
H04M—TELEPHONIC COMMUNICATION
H04M1/00—Substation equipment, e.g. for use by subscribers
H04M1/60—Substation equipment, e.g. for use by subscribers including speech amplifiers
H04M1/6033—Substation equipment, e.g. for use by subscribers including speech amplifiers for providing handsfree use or a loudspeaker mode in telephone sets