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 BE527551ApublicationCriticalpatent/BE527551A/xx
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