How can I find out if someone is in a shelter

That information is confidential all you can do is have them paged or leave message its up to the person if. They respond or not otherwise your not going to be able to find out

Yes they can page the person there

That information is confidential and will not be shared. You can contact the shelters and ask to have a message left for the person you are looking for. Then if the person responds to you that is their decision.