I have to change an old 2000 IVS system with a CAS T1 to PRI. I know nothing about this system except what I've learned in the last few days. The person who previously maintained the system sent me a copy of the ISDN manual and the password. I was able to install the D channel handler OK (I think). However, most of the rest of the programming in the manual is stuff I wouldn't think I have to do all over again. Or do I? Is there a simple procedure for this change or do I have to start from scratch? Any advice greatly appreciated.