Are the "various reasons he gives you" legit?
Once you've become intimate, why would you want to chat online all the time? I'd save that for when we were together. Perhaps you can come to a compromise and you call him once a week and he CALLs you once in the next week (Not MSN Chat) between visits? Most guys don't like idle chatter when they all ready have you sewed up per say.
If once a week is not enough time for you and you think his excuses are lame, then you have to talk to him about compromising and if he won't or absoluetely can't give you more time then you'll have to make a decision to stay with him under the terms he's dictating or, break up and find someone who can give you what you want.
I can't see that he's backing away from you and the relationship... he certainly wouldn't be introducing you to his family if he had thoughts of dumping you, I'm sure.
“The willingness to accept responsibility for one’s own life is the source from which self-respect springs.” ~Joan Didion