Hey, John, don't forget Ring Again on No Answer. But of course, it's usefulness is limited these days.
Quilla -- first turn it on in LD 15, then on the set:
LD 15
REQ CHG
TYPE FTR
OPT RNA
Then turn in on for the set.
Analog:
LD 10
REQ CHG
TYPE 500
CLS XRA
Digital:
LD 11
REQ CHG
TYPE xxxx (put type of set here)
KEY KEY xx RGA (xx = key number to put this feature)
If you do want to use this for All Trunks Busy, you need to program your BARS accordingly. There are a number of additional steps and you should be at least somewhat familiar with BARS programming. Let me know if you need that also.