What are the recommended SIP applications settings?
We recommend turning off the SIP settings as they almost always break SIP, which the phones use as their signalling protocol. Many routers and firewalls have SIP specific settings that manipulate how SIP traffic is handled with the intent to help alleviate traditional issues that applications with specific addressing requirements like SIP have with NAT traversal. This can have other names (SIP Helper, SIP Inspection, SIP Transformations, etc.), but ultimately they all perform a similar function — identifying SIP packets and manipulating them. Again, they should be turned off for use with GoToConnect.