Is it possible to locate a user by his WiFi or Bluetooth connection?

Dear community,


I am currently developing a business idea. One part will be to check into locations. I am wondering whether this is possible without using the location services and without the user´s confirmation about the location by recognizing the phone from its Bluetooth or WiFi information when he is entering the location? Could a notification then be sent so that the program receiving the Bluetooth/WiFi signals from nearby phones could recognize the specific user and e.g. store that he is at the location?


Thank you in advance for your answer!