Setup of Multiple SBCs in an Active/Active mode for different regions, but failover between them.

When we have a scenario whereby a customer has offices in two main global regions, we want to ensure traffic remains within the region where possible. For this post we assume our two regions are the US and the EU. We create and deploy a separate SBC in each region. We want to keep 24*7 phone availability so we install one SBC in Azure US and another in Azure EU. This way we provide the customer with very highly available base for the SBCs. The deployment of the SBC itself is outside the scope of this post but will be covered in another separate post. We configure the SBCs in a failover scenario in that if the primary SBC for the site is unavailable, then the call will automatically route (after 5 seconds – using the -FailoverTimeSeconds parameter) to the SBC in the opposite site. We do this through the use of the - FailoverResponseCodes in the Set-CsOnlinePSTNGateway command. We can find a full list of SIP response codes here: https://www.3cx.com/pbx/sip-responses/ A co...