In my office, I’ve got 2 routers - one router is a basic Fortigate Internet router (192.168.0.1), and the other router is a carrier supplied Cisco router (192.168.0.2) with a SIP trunk (100.100.100.100). The PBX has an IP of 192.168.0.10.
The Cisco router does not have Internet capabilities. When the PBX has a default gateway of the Cisco router, incoming and outgoing calls work fine but cannot do updates or voicemail to email because the Cisco router has no Internet. When I change the PBX default gateway to the Fortigate and set a static host route to get to the Cisco SIP trunk, ie. IP ROUTE 100.100.100.100 255.255.255.255 192.168.0.2, it picks up a call just fine but no audio. Any ideas? As a last resort, I might just have to leave the PBX default gateway pointing to the carrier’s Cisco router and ask them to set a static route for Internet that goes through the Fortigate.