Recommended Settings
STUN/ICE: Disable
NAT Mapping Enabled: Yes
NAT Traversal: Enable sending Keep-Alives only:
on Grandstream HT-701 ATAs this setting is “no, but send keep-alive”
Keep Alive Message: NOTIFY or a UDP PING Packet
For Linksys/Cisco devices, use ‘Nat Keep Alive Msg’ = $NOTIFY or $PING
Never use REGISTER as your Keep Alive message