Considering purchasing my first drone, the Mavic Mini. I have an ancient iphone5c which is incompatible with the drone and app, but functions perfectly for what I need it for. I'm looking to purchase something to use only as a monitor for the drone. I do have an ipad, issued through my job, that I could use, but it seems that it would be far too bulky to be useful. My first thought is to get a refurbished or used iphone 6 plus, which is not unreasonably priced and is supported, and not transferring it to my cellular carrier, but leaving it inactivated. Will this work? Can I log into the APP where I have a wifi signal and remain logged in after I get out of range of a wifi signal? Again, being a novice, is there any need for phone service other than logging into the account, if it is used solely as a monitor? Of course, if I find a phone that appears in great condition and reliable, I may transfer the newer phone to y account and deactivate my antique, but if there is any question of it's reliability or longevity, I'd rather keep my 5c as my cell phone. Are there better, less expensive options for a monitor that will be functional without cell service?