Using mobile hotspot as internet backup

Hi, I have a client who needs an always-on internet solution at their business. They currently have a normal broadband connection, which is spotty at best. I would like to add an AT&T LTE USB adapter, and use it only if the broadband goes down.

Does the Peplink Balance 20 offer the feature I am looking for?
Does it support a LTE USB adapter such as https://www.att.com/devices/netgear/beam.html#sku=sku6610389?
Does it offer seamless integration between the two connections (ie…without having the users ever noticing)?

Thank you!

Yes, the Balance routers all have this feature anf the Beam is indeed a supported modem. When the broadband goes down all traffic will automatically switch over to the USB modem. Thanks.