Social engineering could work. For instance, attempting to message them or call them with a burner phone, pretending to be someone else... I don't really have any idea for scenarios, but in situation like that where all you have is a phone number, sometimes online tools won't be enough, you gotta be clever.
If you can figure out their phone service provider, you could maybe call them with a strategy and try gathering intel from them. Again, I suck social engineering so all I can give you is the basis.
Social engineering could work. For instance, attempting to message them or call them with a burner phone, pretending to be someone else... I don't really have any idea for scenarios, but in situation like that where all you have is a phone number, sometimes online tools won't be enough, you gotta be clever.
If you can figure out their phone service provider, you could maybe call them with a strategy and try gathering intel from them. Again, I suck social engineering so all I can give you is the basis.