Hi there, If I have a system with 3 x ISDN2 connections, and a Patton 4638, and I want 6 DDIs such that there's a number for the main line and 5 numbers for departments, do I need to order any specific DDI configuration from the telco provider? or is DDI mapping and redirection to an available line done by the PBX? i.e. if someone is on the phone on one of the lines, how does the incoming call know how to go to another line? Cheers, Mike.