What will you do if your lover didn't answer you phone in purpose ?

I have encountered this with once a so called good freind of mine. he was very close. But I noticed after some time he purposedly did not answer my call or SMS. I thought that he was avoiding me by this. I was correct. after that he told no, he was not able to take call. But it proved out that he was just avoiding me.

I think he is too busy at that time so that he can't answer the phone. Or he can't hear the phone ring.