Me and my Girlfriend always iMessage each other when she's on lunch (at about 1-2PM.) It works fine usually, but sometimes, more often than i'd like, her messages will stop coming through for no reason, and she will have to ring me to check whether they went through. I pick the phone up, and the moment I do, they all come through at once (My phone rumbles and I can hear the text tone.) The same happens the other way round, my iMessages/texts will stop coming through and then when she picks up the phone, they come through all at once. I don't know whether this is a problem with iMessage, as a similar thing happened when we were texting when she had a blackberry on Vodafone (i'm on O2, we're both on iPhones on O2 now) Is there something wrong with my phone, or could it be a carrier problem? Has anyone else had similar problems perhaps on different networks? We both updated to iOS 5.1 last night, and it happened today, so if it's a software bug, it obviously hasn't been fixed yet.