How to send and receive texts anonymously?

I'm looking for an app for my iPhone that will let people text me anonymously so they can ask me questions and not have me know who they are. My current idea is to just encrypt numerous contacts so that someone else (or I at a glance) won't know know who they are whenever I have an occasion for these text message questions. I was hoping for a more efficient way. All help is appreciated.

Nowadays you need to ask your carrier. But for older phones you can do this in settings, under call (Mostly old Samsung and Nokia Phones, Without touch)