Is this cheating or what??

i think my boyfriend is cheating on me because i will call him and every time i call him he will say ima call u back and dont call me back until 11pm. and then he will be like im sleppy im going to sleep and we be on tha phone 4 like 10 min.he be lying all tha time to me. he cant keep prominses. he will say ima call u back n neva call back. i was just wondering is he cheating or do it sound like he dont wont be with me?