Kevin, There is a ETS 300 047 specs which is part of the ISDN Basic Rate approval based on iCTR3. This specs refers to some clause like : Part 2 5.4 Separation between the ISDN interface and user accessible parts ... Part 3 5.10 Voltage and current limitations under single fault conditions why don't look at this 300 047 ,it may answer your questions
Pierre-Marie RCIC - http://www.rcic.com Regulatory Compliance Information Center
