I am using iOS 9 on a iPhone 5s and sending to a iPhone 4. Settings for iMessage on both iPhones are the same.
In iMessage settings I have ‘send as text’ when
iMessage is not available. Sometimes when I send a message and I know the recipient is not on WiFi at the time and doesn’t have a data plan (has an iPhone) the blue text bubble appears with the blue line moving to the right but then stalls – they don’t get the text message. Later if they do get a WiFi connection the message comes through – usually hours later.
Is there a way to force iMessage to send the message as a text via the mobile telephone system and not as an iMessage via the Internet?
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Paul L’Huillier
Yes, you can do it. I've run into the same thing.
When a message stalls like that, just tap and hold the message. You should then get the prompt with an option like "Send as text message" or something like that. Hard for me to test it, as you can imagine. But give that a try next time.