3CX customers are experiencing issues with some outbound calls due to Private IP addresses in the SIP headers. Some outbound carriers are no longer accepting traffic from Private IP addresses. 3CX has pushed an update for v20 update 6 that allows customers to update to the new 3CX Flowroute template and adjust the Via Header IP address to the Public IP address. This can be done by selecting the new template and navigating to the “Voice and Chat” tab, enabling the “Public IP in VIA Header” setting, entering your public IP address. 3CX customers on v16 or v18 do not need to upgrade or pull a new template, just need to update the IP addresses to Public IP addresses.