What must remain online?
Write down the business functions you want a backup to support. That may be a smaller set than everything that uses your main connection. Share the requirements with your IT team and potential supplier.
What makes the backup different?
Ask about the underlying carrier, last-mile route, equipment and power dependencies. A second plan may still share a failure point with the first. The supplier should explain what separation it can actually provide.
What happens when traffic switches?
Have the provider explain failover, failback and the behavior of the applications you use. Do not assume that every call or active session will continue without interruption.
What are the operating limits?
Review data allowances, plan restrictions, signal requirements, equipment and the capacity needed for priority applications. Ask whether nonessential traffic needs to be restricted while the backup is active.
Who tests and maintains it?
Agree who configures the setup, tests switching, checks readiness and handles faults. Include power continuity and recovery expectations in the wider conversation. Backup internet addresses specific risks; it is not a guarantee against every outage.