DSS1

Digital Subscriber System No. 1 (DSS1), also known as Euro-ISDN or E-DSS1 (European DSS1), is a digital signalling protocol (D channel protocol) used for the ISDN. The interface is also called NET3 for BRI and NET5 for PRI lines. Can also be called CTR4.

DSS1 is a pan-European standard developed by ETSI. In 1989, 26 network operators from 20 European countries decided to develop this standard to replace earlier national protocols (such as FTZ 1 TR 6 or VN3). DSS1 has been one of the keys to the success of the ISDN within European countries (as compared to, for example, the US).

Non-European countries using DSS1 include Australia, Brazil, India, Israel, New Zealand, Pakistan, Peru, Singapore, Taiwan and the United Arab Emirates.