We are often asked how we stay in touch while on the road. Especially as I'm still working, and need to be able to send/receive emails and other files, staying on the grid is important. Many use mobile hotspots or use a similar service with their phone. All of our iDevices have AT&T service, which works ok. AT&T rarely works in rural areas, however. Actually, it barely worked in our old house in Old Town Longmont.
In order to work on the road, we had a Cradlepoint router installed inside the ER. Connected via coax cable to a cellular antenna on the roof, it can pull in LTE or 4G cell service and provide a wi-fi signal in the camper. We have a Verizon SIM card, as Verizon seems to have the most robust footprint for rural service. When recently camped at Sunset Crater, outside of Flagstaff, we could be online and send/receive email, while others couldn't.
This router has a small footprint. It would fit inside a small cigar box. With a 12v power lead, it is velcro'ed to the inside of our air conditioning duct. Rather than remove the vent everytime I want to turn it off or on, I can use my "special tool" (also known as a kitchen fork) to slip between the vents and nudge the power switch one way or the other.
The only downside is cost of data. Verizon is very proud of their data, and on a busy month, we can spend hundreds on data. If there is an iOS update, I wait until we can visit a Starbucks. If you need to stay on the grid, this is a pretty useful device.
Also, when you call Verizon to get the SIM card activated, be prepared to get switched between several customer service people, as few are familiar with the device. Check out www.cradlepoint.com for more info.
FYI, we paid full price for ours, and was not solicited for a review.