I am unable to send texts to non-iphone users, unable to receive texts from non-iphone users, and unable to receive group texts. I just switched last week from iphone 4 to iphone 6. I kept the same #.
Open settings app.
Go to messages
check the selection for SMS.
find "send and receive" and select your phone number. If only your Apple ID is used, you won't be able to send or receive non iPhone text. Double check the settings for MMS also.
