This Technical Basis for Regulation (TBR) specifies the technical requirements under Article 5(g) of Directive 98/13/EC for Terminal Equipment Type 1 (TE1 see [1]) for the telephony 3,1 kHz teleservice to be attached to the pan-European Integrated Services Digital Network (ISDN) at an interface at the coincident S and T reference point for a basic access. The objective of this TBR is to ensure interworking via the network. A test is given for each requirement in this TBR including measurement methods. The terminal equipment may be stimulated to perform tests by additional equipment if necessary. This TBR specifies the Article 5(g) requirements for TE1 that: