Hey,
you need to share some more info about the project, what I understand is: you need a software to filter out phone number list (not sure where phone number are saved now in database or a CSV or excel file? ) whether they are register on your site or app.
I will develop an application in which there will be two sections, Registered phone number leads an unregistered phone number list, so in this way, you can figure out easily.
Further, we can discuss it and start asap.
Regards,
Nabeel Abid