Busy Lamp Light for distant extensions

I have a couple of FreePbx systems ver 2.10 that are connected using IAX trunks. I have a couple of the BLF/DSS Add on modules for two AAstra 6757i phones. I have the buttons set as BLF’s for extensions on the distant system. When we press the button the distant phone is called. The issue is that the light doesn’t show when the extension is in use. Is there any way to make this work?