Assured ISDN Inter-operability ISDN Network & Switch Compatibility With the wide range ISDN signaling protocols and switches National ISDN-1 (NI-1) support, the mobile workforce can travel across the world and AT&T 5ESS Custom still enjoy the high speed digital service without pain. Northern Telecom DMS-100 Custom DSS1 (Euro-ISDN) Universal Compatibility INS-Net 64 The support of "async-to-sync PPP conversion" lets the TA128 Intelligent ISDN TA PC Ca