Any text app can. iPhones can receive (and send, if they're specifically told to) SMS messages. The only problem is if an iPhone user "texts" an Android user with iMessage without specifying text. Then an iMessage is sent, and Android can't handle iMessages. (It's a copyright issue - Apple won't allow anyone else to sell phones that can do iMessage.) Once a specific iPhone sends an SMS to an particular number, it will continue to send it SMS messages unless specifically told to send it an iMessage, so it only has to be done once.