Is it possible to have a landline (not a cellphone, it must be a landline) in

an RV / travel trailer? My husband and I are going to be renovating our house this summer and we're going to be purchasing either a travel trailer to stay in while the renovations are being done. We'll be staying at an RV campground until renovations are finished. I have a job where I use a landline phone (it cannot be a cellphone) and I use a computer that must have an internet connection. I know wireless internet is possible inside an RV but does anyone know if landlines are possible? Anyone know?

you say that you are going to be staying in a campground with the RV?
the campground should have more info on if they allow landline services, and if the camp ground is set up for landline services... there has to be the wiring set up within the campground to get the dial tone from wherever the telephone terminal is to your camp site.

if the campground normally has extended stay visitors it is likely that it is set up for you to be able to install a landline...

if telephone poles need to be installed, or if the wire needs to be run underground from the terminal to your campsite you will most likely be unable to get the service at that location, as you would need permission from the campsite owner to have this work done, as well as pay the charges for such work to be done...

keep in mind, the NID if installed properly will not be installed to the outside (or inside) your trailer, but to a post near your trailer, and should be grounded by the telephone company, you will be responsible to run wiring from the NID into your trailer, and should ensure your trailer is also grounded...