I have an iPhone 4. My text messages are sending. However, I'll be waiting hours for a reply, only to find out that no one ever got my message, or that they've received the message several hours later. This is REALLY inconvenient, especially since I need my texts to go through when I'm checking the bus schedule in an unfamiliar place - if you text a number they text you the upcoming bus times. This just started happening within the last day or so. Please help!