Has anyone investigate where they would go for the wireless service for this device? Is it as simple as getting a sim from ATT or similar for an iPad or android tablet? Trying to figure out what it would cost here in the US to use for failover.
Note that a failover interface typically uses 100MB of traffic per month. So make sure your data plan has at least that much data on it.
T-Mobile has a new plan for a household celluar router they sell. It is priced similar to the way cable is priced.
For a lower offline cost, I have a Google Project Fi sim in my celluar gateway. It cost $10 per GB for the 1st 6GB, then it is free after that. If you exceed 30GB, you could be throttled. You can choose to pay to regain full speed.