Back up internet is redundancy for your business. It is having an alternative option to flip the switch to another internet provider if the main source goes down for whatever reason. It is a must for most businesses to have an alternative source of internet. How many times has work come to a stand still at your home or office because the internet was down? It is kind of like having a snow day in middle school, it may be fun to take a break but it kills productivity.
The 4G man discussed with me a conversation he recently had with doctor.
This doctor was tech savvy, his office incorporated tablets and laptops for all patient documentation. When the internet is down the staff is not able to see patients. Business comes to a stand still patients have delayed wait times or have to be rescheduled. Having a backup option allows business to continue as usual.