REX 100 3G, 4 x LAN (switch)/1 x 3G modem (UMTS): Helmholz
Amazon.com: 4G VPN Router, Industrial Dual Sim 4G LTE WiFi Router 3G/4G Yeacomm YF325 Wireless Modem Router Unlocked with Sim Card Slot, External Antenna Cellular Modem in North/South America, NOT for Verizon :
Raspberry Pi - Huawei HiLink E3256 3G modem to ethernet adapter - Jerry_Jin - 博客园
NETGEAR 4G LTE Broadband Modem - Use LTE as Backup Internet Connection, Unlocked, Works with any Mobile Network Provider (LB2120) : Amazon.co.uk: Electronics & Photo