To produce ETSs specifying the transmission properties of digital PABX systems, to be connected to the public network, and in particular, the transmission characteristics at 2-wire and 4-wire analogue interfaces and at digital interfaces
Integrated Services Digital Network (ISDN) - Basic User Network Interface (UNI) - Part 3: Implementation Conformance Statement (ICS) and Implementation Extra Information for Testing (IXIT) for Interface IB