Cricket Phone Service

my friend called me the other day on his cricket phone . when i picked up i could see we was connected but neither one of us could hear the other person. I then called right back and it ranged once and then his voice came on and then it says this person can't receive messages at this time. his phone is still active but i am unable to leave a message cause it keeps saying he can't take messages at this time. can u explain tht 2 me. this has been going on 4 about 6 days now. thank u 4 your help