Is any second internet connection enough?
No. Two circuits may share carrier infrastructure, a building entrance, power or network equipment and fail together.
What should a failover design include?
The design should consider provider and physical diversity, automatic switching, application behavior, power backup and a regular testing schedule.
- Separate providers where practical
- Different access technologies or routes
- Gateway and switch resilience
- Battery backup for critical equipment
- Documented failover and restoration tests
Will active calls survive a circuit change?
Sometimes, but not automatically. The phone platform, firewall, addressing and failover timing all affect whether active sessions continue or must reconnect.