Up close with iOS 5: iMessage

12.10.2011

Because iMessage uses 3G and Wi-Fi to transmit its messages, it's occasionally not the most reliable to use on an iPhone in the case of a natural disaster or 3G outage. This is where the Send As SMS toggle comes into play: If you have this option enabled, you'll be prompted to send your message as a traditional SMS instead in the event that the iMessage app can't transmit something over a data network.