iMessages Picture/Video Not Delivered
For the past few months, with increasing frequency, sending pictures or videos through iMessages on my iPhone to other iOS devices results in a "Not Delivered" response.
At this point, around 25% of the time, when I try to send a picture/video via iMessages, the progress bar at the top of the screen appears as though the picture/video is sending. Upon the progress bar reaching 100%, the picture/video seems like it was successfully sent; however, 10-20 seconds later, the red "!" button and red "Not Delivered" text appear by the picture/video. Sometimes the "Try again" option will work after several attempts; other times, I have to send it as a text message in order for it to go through.
This issue does not appear to be related to certain contacts, as it happens randomly to all my AT&T iOS recipients, as well as Wi-Fi iPad recipients.
I have spoken to some of my friends/family about this, and this issue seems to be widespread, at least among AT&T users.
iPhone 4S, 64GB, iOS 6.1.3, AT&T
iPhone 4S, iOS 6, 64GB