OpenPhone - Simplest way to own a business phone number
Burner - Disposable phone numbers -- now with MMS photo support
Hushed App - Hushed App will allow you to receive a Secondary Phone Number for Private, Long-Distance...
TextNow - TextNow is a mobile virtual network operator (MVNO) that provides a free phone service to users by using other cellular networks coverage.
Numero eSIM - Numero eSIM is a phone-number app that makes voice and data possible anywhere in the world, for free.
Sideline - Sideline™ is the free 2nd number for your smartphone. It uses your existing carrier network so your 2nd number works anywhere your cell phone does.