One way to have a cheap telephone system is to use an old SL-1 system with the processor cards from an Option 21. The first time I did this we hired a company that charged a foutune to reprogram the Option 21 software to work on the older SL-1 system. They said it was a tricky procedure to remove the option 21's superloop programming. I have tried to do it but cannot get it to allow me to X28 in load 97. If this is not done you are limited to using every other slot for the QPC414's and on one system it keeps resetting on errors in the non-existant super loop. On one occasion the system was down for 10 minutes while it kept resetting! One solution is to keep the Option 21 cabinet, but then you cannot battery backup the processor. Any ideas?