You can create a FortiVoice LSG topology by using Multiprotocol Label Switching (MPLS), a virtual private network (VPN), or software-defined networking in a wide area network (SD-WAN). When using a VPN, you can set up VPN tunnels between the branch office and the main office to avoid configuring rules and policies for various traffic types. Calls between extensions are always routed through the main office system, so a VPN tunnel setup between branch offices is not required.
The main office manages configuration information for the branch phones and offices. The main office has the following management functions:
- Creation of all branch office extensions: The main office pushes all branch office extensions to each branch office.
- Storage of all voicemail messages: The main office, not the branch office, stores all voicemail messages.
- Phone registration: Phones register with the FortiVoice phone system at the main office and with the FortiVoice LSG unit at the branch office.
Configuration changes required at each branch office are limited to the following settings:
- Administrator accounts
- Network configuration settings
- Outbound call routing for failover scenarios
- Branch SIP port setting. If the branch office is using a non-default SIP port, then you must make sure to include that branch SIP port setting when configuring the survivability branch management on the FortiVoice phone system at the main office.
The following image shows a FortiVoice LSG topology example: