- Put "VoIP GW" in 'SIP server networks' and "Internal (Network)" in 'SIP client networks'.
- Create a NAT rule 'CallCentric -> VoIP Protocols -> External (Address) : DNAT to VoIP GW' {leave Destination service empty and select auto firewall rules}.
- Create a Firewall rule 'VoIP GW -> VoIP Protocols -> CallCentric : Allow'.
- Make sure you have a masquerading rule 'VoIP (Network) -> External'.
- Put "VoIP GW" in 'SIP server networks' and "Internal (Network)" in 'SIP client networks'.
- Create a NAT rule 'CallCentric -> VoIP Protocols -> External (Address) : DNAT to VoIP GW' {leave Destination service empty and select auto firewall rules}.
- Create a Firewall rule 'VoIP GW -> VoIP Protocols -> CallCentric : Allow'.
- Make sure you have a masquerading rule 'VoIP (Network) -> External'.