This is an awesome modem/router.  These are hard to find and they work great.

Primary DSL with fail-over to Broadband (for use with your USB broadband modem).  Note: 4G USB modem NOT SUPPLIED!!

For cost-effectiveness, I use DSL.  When DSL goes down, this modem/router is smart enough to fail-over to my 4G Broadband USB modem.  Just plug in your own USB broadband modem into the modem/router interface.  Personal experience: should DSL goes down, my entire house continues to run as if all was well.  Very nice for those who have a USB broadband modem.  Note: check manufacturer documentation to ensure your USB modem is supported.

Personal note:  I like USB broadband modems.  When I am home, I plug it into this router's interface for enhanced fail-safe household operation.  When I am on the road, I unplug the USB router and take it with me for use with my laptop.  Most set-ups like this require a dedicated/stationary broadband gateway.

This YouTube video explains it well:

Click here:  This video explains it well

Ideal solution for those that require an enhanced fail-safe internet connection.