I would guess it's the input to the Bogen where you have the issue. You have three options as a paging input on that module. (set by dip switches) You can set the Bogen to be called as if it's a station on the PBX, or use a loop or ground start trunk port, or - a page port setting. If you use the page port setting, you have to also provide a contact closure on pins 2 and 5 of the 6 pin input connector.