Unstable BLF behaviour FreePBX + Grandstream GXP 2160


Since not so long ago all BLF on our GXP 2160 (around ten phones) are suffering from unstable BLF behaviour. This is after rebooting phone or change just one BLF Multi purpose key, BLF is working fine: when a peer is ringing, BLF is blinking red. When a peer is busy, BLF turns to static red.

After around five minutes, all BLF in a GXP freeze. This is they not change anymore: if some BLF were green, they keep green. The ones that were in red or blinking keep static or blinking. If we reboot the phone or change some BLF parameter on the phone web, BLF works fine…for around five minutes.

We captured SIP traffic in the phone and we debbuged peer in Asterisk CLI, and it seems that subscribe and notify messages are not sended when BLF are not working. My conclusion is that there are some misconfiguration in our FreePBX…moreover, we have another one (13.0.167) and if we register the same phones in this one, BLF seems to work properly.

I am really newbie and I don’t know where in FreePBX/Asterisk can I look for the mistake.

Any suggestion?

Thank you very much!