Q: Text messages from iPhone 6+ will not transmit to non iMessage users

My iPhone 6+ has all of the Apple updates.  When I send SMS or MMS to iMessage users, they transmit.  When I send SMS or MMS to non iMessage users such as Androids and Google Voice, SMS and MMS do not transmit and reflects, "Message Send Failure."  I have tried resetting the phone, changing iMessage and phone settings, and deleting and reentering contacts and their numbers in the address book.  Why will my messages not transmit to non iMessage users?