IVM doesn't answer after 5 minutes

digixit

I use IVM with voip. it answer the first call and also other successive calls, but if no call is made in 5 minutes it hangs and doen't answer anymore

until I press On/Off button and it register again to the Voip service. Again it answer to any call but if inactive for more than 5 minutes doesn't answer.

[deleted]

It's likely the ports on your router/firewall are timing out (if they aren't manually forwarded to your computer), and effectively closing the connection.