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?