How do you know who is the mysterious person who suddenly texted you?

The best way is to charge him the phone bill and then let you determine your name. Then you'll know.

But the only drawback of this method is that it costs money.

The other way is,

Check his location and see if you know anyone there. 、

Last one, dial another phone. Lie to him, as for how to lie to yourself.

That's all I can think of.