Digital Subscriber System No. 2

{{One source|date=June 2025}}

Digital Subscriber Signalling System No. 2 (DSS2), as the successor to DSS1,[http://www.etsi.org/deliver/etsi_i_ets/300100_300199/30010201/01_60/ets_30010201e01p.pdf Integrated Services Digital Network (ISDN); User-network interface layer 3 Specifications for basic call control] is also a digital signalling protocol (D channel protocol) used for the B-ISDN.