How it works
A fallback destination should cover busy, no-answer and unreachable cases, not only a complete PBX outage. Call handling rules determine the order of destinations, ringing time and fallback behaviour. The exact result depends on PBX configuration and whether endpoints are reachable.
Business example
If agents are busy or an office is unreachable, the system routes the caller to another team or offers a callback.
What to consider
Test busy, no-answer and simultaneous-call cases. Assign responsibility for maintaining routing rules and provide a clear next step when the preferred destination is unavailable.