Sounds like you're using the Norstar auxiliary relay to trigger ringing over the PA system.
Is there a jumper on YL/BN BN/YL on the ICS auxiliary equipment block? If so, put a short on it. If ringing is heard over the PA system, you'll know the PA system side is okay.
You may be using an analog extension or the auxiliary relay to trigger the night ring option on a Valcom page control instead. Or maybe the built-in night ringer on a Bogen 70V paging amp. There's numerous ways to install ring over page.
What type of paging system/ringing device are you using?