If by WISP you mean Wireless Internet Service Provider then yes, I have. About 10 years ago. When people had a choice of expensive DSL of cheap wifi. It still makes sense in rural areas, where broadband is simply not available or your only choice is expensive Comcast of some other scumbag company.
What you need to realise is that you will run into bunch of legal bs, paperwork, and other crap. We tried to rent a space on a tower owned by electric company, and the requirements they gave us were insane, just to even be able to be considered. Planning, architectural designs, some regulatory bs, we were looking at spending thousands before they would even consider renting us the space. And rent was nuts too. It was much easier dealing with churches, they would allow us to mount antennas in exchange for free internet, no money involved.
There also were technical issues, that most people don't realize, I can talk about it more if you want to, but generally, if you have other options available, don't mess with WISP.