One of my friends is not receiving my text messages

     I have a BlackBerry Storm 1 and for some odd reason, my friend who also has Verizon (I believe) has not been receiving my messages.  For example, I sent him a message and then a few hours later he sent me a message saying, "Hello?". After that i sent him four more text messages but nothing seemed to go through, until finally i sent a fifth message and he replied with "Finally! Smiley Sad". So clearly, he is not receiving most of my texts.

      We continued to text but it stopped once again in the middle of our conversation.  I sent him more texts, but so far I have not gotten any messages from him for about a day now.  I've called *228 and have done both options 1 and 2.

     Him and I have had numerous experiences like this, but this one has to be the worst. Usually I only have to send one more text in addition to the one he didn't receive. Anyone have any ideas on how this could be fixed? I do realize that it could be his phone as well (he claims his phone is messed up).  I believe that all of my other friends receive my messages, although I'm not entirely sure. Any help would be great. Smiley Happy