Sometimes my boyfriend doesnt answer the phone? is he cheating?

OK so on several different occasions my bf wont answer the phone and I could have just gotten off the phone with him and ill try to call back an hr later or so and won't get an answer to the next day it has happened three or. four times and he'll claim he fell. asleep and I thinl to. myself how did. u fall asleep that fast? Today. we. talked all day and about 6:40pm was the. last time I talk. to him I tried calling him at. 7:50pm and haven't gotten a answer from him. since then I hjust sent him a long message. saying I'm tired of him doing this and I'm done. because why can't he stay by the phone I do the. same for him I gotta hear from him the. next day I. dont have a car to check and see I. just go off his word. I know his ex still. calls him and all and I don't. wanna seem insecure but I don't.