A person Y needs to send a SMS to a person X through my app, but the person X does not have to know the cellphone number of the person Y. What is the best way to achieve this scenario ?
The number show/hide is managed directly by the network provider. Anonimous SMS are NOT supported by any of them. Phone calls may be, but, even if you set it to 'hide' on your phone settings, the Network provider may not allow it and ending up by showing it in the receiver side.