Ring Intercom on Urmet 1750/1

I am having an issue where when I call the phone apartment from the central panel and the central panel has a high pitch squeal/ring sound on the line with the Urmet 1750/1. I have reset the Ring Intercom a few times and tried switching C9 an C10 around Between C10-LI C9-NE and vice versa but having the same issue regardless of the wiring when calling from the central panel. I have tried adjusting the volumes and amplifier settings. It still has the high pitched squeal/ring. It's insanely loud. I can answer on my phone. I can unlock the door just fine. I can hear the voice from a phone over the central panel but it is overpowered by the loud squeal/ring. I can't keep going out to the central panel to test because the sound is so loud that the other residents probably think I'm doing something sketchy.