I've been thinking about this for a few days. My partner has a pair of mini horses that I thought might be nice for her to be able to check in on remotely. They graze elsewhere so she normally calls in once a day to move them (they seem at risk of eating too much grass).

I've had a quick look at dedicated trail cameras but I was wondering how hard it would be to simply use an old phone. I have a few in cupboards that function and a ZeroLemon external battery that I use on long time lapses (GoPro or MILC camera).

I just wondered if I simply shoved it on a fence post and found some app to do it? The grazing paddock has good cell coverage, I thought an old GoPro might have too wide a field of view to actually see much but do have an older one I don't use much. 

Or I just bite the bullet and buy one of those dedicated hunting/trail cameras.