How much data does backup internet use?

From the FAILOVER5 team at Twisted VoIP, Chandler, Arizona · Updated October 2026

A backup line only carries traffic while your main connection is down. For most businesses that's a few hours a year, so the data needed is much smaller than people expect. The one thing that changes the answer completely is which devices you allow onto the backup.

The light stuff

The systems most businesses need during an outage barely use any data:

Card payments: a few kilobytes each. Thousands of transactions fit in less data than one short video.
Cloud point of sale, scheduling and practice software: small, steady traffic, mostly text.
Email without big attachments.
Internet phone calls: roughly one megabyte per minute per call, depending on the phone system.

The heavy stuff

These are the things that turn a small backup bill into a large one. Keep them on the main line, or limit them on the backup:

Guest and customer WiFi. People stream video while they wait.
Security cameras that upload to the cloud. Recording locally is fine; streaming to the cloud is not.
Video meetings, streaming music and TVs.
Cloud backups, software updates and big file syncs.

Three worked examples

A small restaurant puts its POS terminals, kitchen screens and delivery tablets on the backup and leaves guest WiFi off. A two-hour Friday night outage uses a few hundred megabytes. Even several outages a month would fit easily in 10 GB.

A medical clinic adds phones to the backup. An all-day outage with steady call volume might use a few gigabytes on calls, plus a little for the EHR and check-in. A 20 GB plan covers that with plenty to spare.

A ten-person office wants video meetings to carry on during an outage. An hour-long video call can use a gigabyte or more per person, so a full day of meetings adds up fast. That office should look at 50 GB or 100 GB, or decide that meetings move to phones during an outage.

How to keep heavy traffic off the backup

Put guest WiFi on its own network, separate from your business devices. Most business routers support this.
In your router's failover settings, choose which networks or devices are allowed to use the backup connection.
Set cloud backup and sync software to pause or throttle on a metered connection where it supports that.
If your router allows it, give phones and payments priority on the backup.

When cellular is the main connection

Job trailers, food trucks, pop-ups and rural sites that use cellular as their only internet are a different case: everything runs on it all the time. Size those plans like a regular internet connection, from 100 GB up, or T-Mobile Ultra 1200 (1.2 TB) where T-Mobile coverage is strong.

FAILOVER5 plans

All plans are month to month, so you can move up or down after you see what you actually use. Static IP is available on Verizon plans for $3 a month more.

10 GB: $88 a month (Verizon or AT&T)
20 GB: $123 a month
50 GB: $175 a month
100 GB: $228 a month
200 GB: $350 a month
T-Mobile Ultra 1200 (1.2 TB): $279 a month

Watching your usage

You don't have to guess forever. FAILOVER5 customers can see each line's data use in the customer portal and get an alert as a plan fills up, so a camera or a guest network that slipped onto the backup gets caught early instead of at the end of the month.

After an outage or two, look at how much data it actually used. Most businesses find they can stay on a smaller plan than they first chose; a few find something heavy on the backup that shouldn't be there.

Get a quote for your business

Tell us where you are and what needs to stay online. We'll check which carrier is strongest at your address and recommend a plan and router. Plans start at $88/month, month to month.

Already know what you need? Build and order it yourself or compare plans. Or call 800-732-0846.