Thanks everyone. Got em all straightened out now. Everything said above is correct. To summarize:

20-08-10 and 20-09-05 COS to allow switching from ring to voice announce.
20-02-12 system - Set to Signal, so ext. rings.
15-02-68 per ext.- Set to Signal, so ext. rings.
Then the originating ext. has the option to press 1 to voice announce.

Jim