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Publication of BE710198ApublicationCriticalpatent/BE710198A/xx
H04Q1/00—Details of selecting apparatus or arrangements
H04Q1/18—Electrical details
H04Q1/30—Signalling arrangements; Manipulation of signalling currents
H04Q1/44—Signalling arrangements; Manipulation of signalling currents using alternate current
H04Q1/442—Signalling arrangements; Manipulation of signalling currents using alternate current with out-of-voice band signalling frequencies
H04Q1/4423—Signalling arrangements; Manipulation of signalling currents using alternate current with out-of-voice band signalling frequencies using one signalling frequency