This revision was issued purely in order to correct the value for Loop Model 3 is 0.25Y, 0.4mm PE in the v1.5.2 the value is 0,5Y - Below the work item scope of TS 101 135 v1.5.2 - This work item studies the problems involved in combining the transmission of ISDN-BA (or POTS) and 2048kbit/s data transmission over HDSL transmission systems. The output of the work item shall be the addition of a new sub-clause 7.7 for insertion in a version 1.5.1 of TS 101 135 V1.4.1. The purpose of this work item is to allow the problems involved in combining 2048kbit/s and ISDN-BA (or POTS) to be solved separately from the work being carried out under TS 101 135 V1.4.1, and if necessary to find a solution that would not be permitted within the scope of ETR152, for example a modification of the basic HDSL core frame structure. This allows TS 101 135 V1.4.1 to be completed according to schedule, and allows sufficient time to find an optimum solution for embedding ISDN-BA in HDSL systems.