There are numbers of available methods for firewall traversal. Each has its own benefits; many have significant drawbacks. These drawbacks impact security.
The choice of method for traversing firewalls/NATs determines the amount of control and security you maintain of your network. Is your security best left to your firewall administrator? The individual user? Your service provider? Also, does the solution need to work with all operators, or only one specifically?
How SIP-compliant does it really need to be? Will SIP interoperability issues affect security? The answers can help determine which method of firewall/NAT traversal is right for your network.
For additional information on Ingate's NAT Traversal or for a quote on an Ingate Session Border Controller, please contact firstname.lastname@example.org.