Starting a Wind Phone where you live
The phone is the easy part. Everything around it is the work.
Building the object itself is a weekend project: an old phone, something to house it, a place to bolt it down. That part is covered elsewhere, and the ones already standing are listed here. Putting it somewhere other people can actually use it, and keeping it usable for years, is the longer job, and it is the part most people skip thinking about until it is too late.
Who to ask first
A Wind Phone on your own property needs no one's permission but yours. Anywhere else does. Parks departments, churches, hospices, and schools are the places that most often say yes, because each already understands why someone might need a place like this on their grounds. Start with whoever manages the land, not whoever you think would be sympathetic. A sympathetic staff member without authority over the site cannot give you permission that will hold.
Be specific when you ask: what it is, roughly how big, where you would put it, who will maintain it, and what happens if it ever needs to be removed. A vague request is easy to say no to. A specific one gives someone something they can actually approve.
Where it goes
Somewhere a person can stand alone for ten minutes without being watched, but not somewhere isolated enough to feel unsafe reaching at night. Near a bench, if you can manage it. Off the main path, close enough that visitors do not walk far to find it. Consider who else uses the site: a churchyard also used for weddings, a school also used by children who did not choose to be near a memorial to death. None of that rules a site out. It just means asking the people who use the space, not only the people who own it.
Weather, upkeep, and vandalism
A phone left outdoors will weather. Wood swells and splits, paint fades, hinges rust, a rotary dial left exposed to rain will eventually seize. Plan for someone, ideally more than one person, to check on it every few months: does the booth still close, is the phone still there, has anything been left that needs clearing before it rots or draws animals. What visitors are asked to do and not do only holds if someone occasionally checks that they are doing it.
Vandalism happens, more often to phones in unattended public parks than on private or religious grounds. A phone that is stolen or broken should be replaced without much ceremony. It was never a shrine to the object itself.
Who answers when someone is in trouble
Occasionally, someone at the phone will be in more distress than the phone alone can hold. Decide in advance who that becomes, before you need the answer under pressure: a hospice chaplain if it sits on hospice grounds, a school counsellor if it sits on school grounds, a sign with a crisis line number if the site has no staff at all. You are not signing up to provide therapy. Whether the phone helps anyone is worth sitting with before you build one, not only after.
Say what you need to say. The line is connected to nothing: no one hears you, nothing is recorded, nothing is stored.