using iPhone 5 without data

i want to cut back the monthly costs of my phone. i want to use my phone/text messaging and non data apps when i'm out, and use anything else when i have wifi. the primary problem i have encountered so far is that when i turn the data off on my phone, and turn off iMessage, so my phone no longer tries to send text in that format, i cannot receive texts from anyone who is using iMessage. i can't just go around and tell everyone to not text me with iMessage, or even know who has an iPhone or who doesn't that i text. how can i get around this, so i can freely send and receive texts with whoever i want, while still functioning with the data turned off?

thanks.