If calling to vodafone , if user is not attending phone , does u get message that user is busy on another cal?

[Mohammad S]

I was calling to one of my friend repeatedly , some time i used to get message that " the telephone no which u have dialled is busy on another call " .

I asked him , he told that he was not talking to anyone , his phone was in silent mode ,
Is it possible . He is using vodafone .