How to setup #G/4G Modem Backup
SonicWall TZ series manages 3G/4G modems

https://www.sonicwall.com/en-us/support/knowledge-base/170505752336995


Supported Modems and Service Providers:
Wireless Broadband Cards and Devices (Wireless WAN USB devices) supported by SonicWall Firewalls

https://www.sonicwall.com/en-us/support/knowledge-base/170505473051240