I need someone to confirm this is how I should have my parents Uverse router setup...

Static IP set to MAC Address of VOIPo adapter
Firewall setup...
UDP ports 5004-65000 assigned to static VOIPo IP
user defined application SIP assigned to static VOIPo IP

My parents have issues once a month, where they pickup the call and get a busy signal. I usually log a ticket for them, but then it starts to work. This is all after I power cycle the router and VOIPo adapter

VOIPo adapter is grandstream HT505

Thanks,
Justin