Conversations

Why do some conversation just get awkward at times  ??? This guy i met online gave me his number i called him up for a chat and guess what we had only silence. I mean why sometimes there is nothing to talk about even its not some stranger but a friend you have known since long. May be its just me who isnt a very outspoken person , and find it difficult to keep a conversation going. Hope someday i'll be able to have some non-stop conversation with someone !!!