Hi Alex,
I really appreciate your reply. The Send as SMS slider is already on.
Unfortunately the problem is much more complex than this and is a deeper design flaw, maybe related to "too smart for its own good" features.
Let me explain:
When I try to send a message to my wife (no Data, just cell) from my iPhone (with Data) it sends as an iMessage, shows blue and even says "Delivered". But she does not receive anything.
If I turn OFF iMessage to try to send as an SMS, it ignores this, remains blue and says "iMessage" in the message entry field and after I hit send, it displays the error message"iMessage must be turned on to send this message".
To compound this flaw, the option to "Send as Text Message", which used to appear when you put your finger on the message text itself, no longer appears because it's been replaced with the "cute" response icons, "haha" "?" etc.
A case of new too-cute features destroying basic necessary functionality, perhaps?
I finally came up with a cumbersome workaround:
To stop the message field remaining blue, I attempted to SMS by typing in my wife's mobile number manually. This failed because the "too clever" system immediately recoginsed the number as hers and went blue again. (All this is happening with iMessage turned OFF, remember)
The only final workaround was to delete my wife's mobile number from her contact card. The phone then ceased to see that as belonging to anyone and stayed in green SMS mode.
This is an awful workaround because it means I have to go through these motions every single time I want to switch from messaging someone with data or someone without data.
I'd still really like a proper fix if one exists that you or someone at Apple knows of, or if not, for this to be elevated to official "bug" level for fix in a future iOS update. I'm not the only person I know having this issue.
Your help in getting this sorted would be great. :-)
Thanks.
Note: this problem is happening for us in both the Philippines and Australia across multiple cell networks - so probably not a network issue.