This is a fairly recent development. But I'm both, hearing from friends and family that use iPhones, and experiencing this issue myself. You send a text message using iMessage, and get a notification that the message has been sent. But the person that you sent the text to never receives it. This is compounded by the way that Apple delivers, (or fails to deliver), regular texts by other means if iMessage is not working. The end result is that you cannot reliably send a text by either means. Some users have been attributing this to the new IOS upgrade that just came out for iPad2 and iPhone 4s, but I have not upgraded to this new version because I have an iPhone 6 Plus. Still, the issue seems to be affecting me just the same. This is a critical issue, as a huge number of users communicate using iMessage. The fact that Apple also seems to be interfering with delivery of regular texts is making this issue even worse.