The internet went down on a Tuesday at 10:17 AM.

It wasn't a catastrophic failure — just a fibre line somewhere upstream with a problem that the ISP took until 12:45 PM to resolve. Two and a half hours.

Eight people in the office. No internet meant no cloud applications, no email, no VoIP phones, no ability to pull files from the shared drive. Two of the eight were on calls with clients that dropped mid-sentence. One was in the middle of submitting a proposal by deadline. The proposal went in late.

By the time service was restored, they'd lost an estimated $3,800 in billable productivity and missed one deadline that damaged a client relationship.

An LTE failover SIM on a dual-WAN router would have cost $40 a month. The failover would have kicked in automatically in under 30 seconds. The clients wouldn't have noticed.

What internet failover actually is

Internet failover means having a second internet connection that activates automatically when your primary connection fails. For most small businesses, the primary connection is fibre or cable from a major ISP. The secondary connection is typically an LTE/5G cellular modem using a data SIM.

A dual-WAN router (most business-grade firewalls support this natively) monitors both connections continuously. When it detects the primary has failed — typically within 10–30 seconds — it shifts all traffic to the secondary without any user intervention and without dropping most active sessions.

When the primary restores, the router detects this and shifts back. The whole event is transparent.

What it requires

Hardware: A router with dual-WAN capability. Most business-grade firewalls (SonicWall, Meraki, Fortinet, Ubiquiti) support this natively. Consumer-grade routers typically do not.

Secondary connection: An LTE or 5G modem with a data SIM. Major carriers in Canada offer business data SIMs without voice service for $30–$60/month depending on data allowance. For failover purposes (not primary traffic), even a 20GB SIM is usually sufficient.

Configuration: The router needs to be configured with the right health check targets and failover thresholds. This is where most DIY setups fail — improperly configured failover sometimes doesn't trigger, or triggers at the wrong time (brief packet loss vs. actual outage).

What a proper failover setup looks like

Health checks: the router pings an external address (Google DNS, Cloudflare) on both connections every 5–10 seconds. If the primary fails to respond for a configurable number of consecutive checks (typically 3–5), failover triggers.

Traffic priority: when running on the secondary (LTE), bandwidth-intensive traffic like video streaming and large downloads can be deprioritized to preserve capacity for business-critical applications like VoIP, cloud applications, and email.

VoIP configuration: if your phone system uses VoIP (Teams Phone, RingCentral, etc.), the failover needs to be fast enough that active calls don't drop. Sub-30-second failover usually preserves active calls; longer failover times typically don't.

Monitoring: your IT provider should get an alert when failover activates. Running on cellular for an hour is fine; running on cellular for eight hours without knowing is a problem.

How to calculate whether it's worth it

Take your average hourly loaded cost per employee (salary + benefits + overhead, typically $45–$90/hour for a Canadian small business employee). Multiply by your headcount. That's the cost of a single hour of downtime.

For an 8-person office at $65/hour loaded cost: $520/hour. One two-and-a-half hour outage: $1,300 in labour cost alone, before the missed deadline and the client relationship.

Against $40–$60/month for an LTE SIM that prevents most of that: the payback period is less than one incident.