How do I connect two SIP Trunks to Grandstream UCM?

Description

In some countries, the providers of SIP trunks deliver a private IP for the routing of calls on their SIP trunks, in these cases, it is necessary to manage static routes to redirect outgoing calls on their private network or interface. In dual-mode, the UCM6XXX is able to handle a different network per individual port and a default interface. LAN port and WAN port are not independent WAN ports.

How to

In this scenario, we are using a Mikrotik router to connect with interface 2 through LAN with connectivity provided by primary SIP provider. Select Dual as the Method under UCM’s Web UI > Network Setting > Basic Setting

1. On the Mikrotik interface, configure WAN from primary SIP provider destinated to your LAN Network, for eg. 192.XXX.XXX.XXX/24
2. On the UCM‘s Web UI > Network Setting > Basic Setting , configure Interface LAN 2 with LAN IP (different than LAN Gateway) 
3. Configure Interface LAN 1 with the secondary SIP Provider’s WAN configuration 
4. Set LAN 2 as Default Interface under Basic Setting 
5. Add all the necessary static routes to LAN1 and to LAN2 (be sure to include all the SIP provider subroutes or SBC’s if any) 
6. Do not worry for the LAN1 Gateway as you can’t configure more than one gateway to the UCM, instead, add the gateway to the Static Routes under Network Setting > Static Routes tab so it can be reachable. 
7. Ping to all the routes from UCM’s Maintenance > Network Troubleshooting > IP Ping to see if you can reach them. 
8. Note: Static Routes should be configured with Subnet Mask 255.255.255.255 and secondary SIP provider gateway IP with no gateway (leave blank).