ＩＳＤＮalso: アイエスディーエヌFreq.FrequencyTop 50,000Meanings1nounISDN; integrated services digital networktelecommunicationsTelecommunications term for a digital network standard; now largely historical.ＩＳＤＮは１９９０年ねん代だいに広ひろく使つかわれた通つう信しん方ほう式しきです。ISDN was a widely used communication system in the 1990s.
