Inbound issue when caller hangs up (Ported from Voipo - HT702)

I am a Voipo ported customer and using an HT702 - I have everything setup and working (Finally) but am getting a weird issue. When I get a call and the caller hangs up - I get the busy noise on my phone. I have reached out via a ticket but am not getting any response - any one have any ideas? Thanks in advance…

This appears to solve the problem:

Set

Loop Current Disconnect: to YES
Loop Current Disconnect Duration: to 500 or 600