Get cellphone number (from SIM card) of mobile phone via WiFi

Hello community I would like to ask if this project is feasible, I am new to arduino and I read that there are certain modules to connect to a WiFi and get the data (the clients, etc).

Here is the process that I'm thinking of:

  1. Arduino connects to a WiFi network (this wifi network is my network, assume I know the credentials).
  2. Arduino gets the IP(?) of the clients connected to it.
  3. Arduino then gets the mobile number of the client.
  4. Arduino interface with PHP and send sms via sms gateway (well this is possible).

My concern is how can I get the mobile number without actual user input. If there are any suggestions on how could I get the mobile number of the cellphones within a radius, let me know. Thank you!