I have an iPhone 4 w/ Verizon, my friend has an iPhone 5 w /Verizon. A couple weeks ago our iMessaging stopped working, they no longer receive my messages. I receive theirs fine. My phone is always telling me anywhere up to an hour later that the iMessage didnt go through (little red !) and gives me the choice of resending or sending as a text. I resend as a text and it USUALLY works. This only happens when I text this certain friend. My iMessaging/ texting works fine with everyone else. Also we are able to connect and call even using facetime without any issues. Imessaging is turned on on all of our devices. Help!!