Hint problem

Hi.i’ve a phone " snom 320 " When I put in extension.conf ?hint", my lights light when the people are on line but it works only locally. My problem is when i use the iax by the VPN: Lights does’nt work when a station is in line with the iax. Two networks are connect in vpn and the lights doesn’t work.I will like that my lights ignite when a phone is on line with the iax.
How can i have the busy’s occupation when i call somebody whis is on line. At this moment, I have a music on hold but not busy’s occupation. thank you